Javadoc FAQ

   
   
 
A. Using the Javadoc Tool
 
 
A1. Where can I find the Javadoc tool and its documentation?
A2. How do I write Javadoc doc comments and tags?
A3. How do I run Javadoc?
A4. How do I run Javadoc from within a Java application?
A5. How can I tell which version of Javadoc I'm running?
A6. How do I write a shell script or batch file to run Javadoc?
A7. I'm planning to upgrade to a newer version of Javadoc and am wondering what kinds of problems I might encounter?
A8. Is there an easy way to print the many pages generated from Javadoc, such as using PDF?
A9. Can I incrementally build a document from different runs of Javadoc?
A10. I'm using -link or -linkoffline but some of my external links do not show up. Why is this?
A11. Is there a way to redirect links between multiple independently-built HTML Javadoc trees?
A12. How does your implementation of Javadoc work?
A13. Can I run javadoc on source files from other languages, such as C, C++ or VisualBasic?
A14. How can I create custom Javadoc tags?
A15. Where can I find code examples for the Java API?
A16. How can I exclude or skip certain public members or classes from being documented?
A17. How would I create a makefile for documenting arbitrarily large libraries?
A18. May I see the slides presented at the JavaOne Javadoc Birds-of-a-Feather session?
A19. How do I generate documentation for packages that contain a package.html file but no java files?
 
 
B. Troubleshooting: Bugs, Errors and Warnings
 
B1. What bugs are in Javadoc?
B2. How do I submit bugs and feature requests?
B3. How do I redirect error messages to a file?
B4. I just can't get Javadoc to work over my entire source code; what do you suggest?
B5. I run out of memory -- how much is needed, exactly how do you call Javadoc, and how long does it take?
B6. Why aren't the memory flags (-J-m) recognized in Windows?
B7. When I run Javadoc on my source package, some links are not generated.
B8. In Javadoc 1.2.2, when using @see or {@link} tags to external API, and links to methods, fields and constructors are missing.
B9. Why do I get the warning "Class or Package not found in @see/@link tag" or "reference not found"?
B10. The class comments are missing from the generated docs, but are in the source code.
B11. When I run Javadoc, I get the following exception warning: "Method X declares that it throws class Y, but there is no corresponding @exception item." What does this message mean?
B12. I copied all of my .java files from their package hierarchy into a single directory so it would be easier to run Javadoc on them, but it doesn't work.
B13. I am documenting 33 packages and added a new package to my javadoc command but this created a "No source files" error.
B14. I get the error "Class xxx already defined".
B15. I get the errors "FileNotFoundException" and "Fatal Exception".
B16. Using Javadoc 1.4.1, I get an InvocationTargetException when I set the classpath.
B17. Why do I get so many @serial warnings , including warnings about private fields?
 
 
C. Customizing the Javadoc Tool
 
C1. How can I modify the standard doclet to produce links to source code from the API documentation?
C2. How can I change the colors and font sizes?
C3. How can I eliminate the HTML frames in the javadoc look?
C4. How do I document Java platform classes using a later version of Javadoc?
C5. How do I workaround the new restriction in 1.4 that HTML tags cannot be used around parameter names?
 
 
D. Developing with the Javadoc Tool
 
D1. Where can I find the source code for the Javadoc tool and standard doclet?
D2. Where can I find the com.sun.javadoc and com.sun.tools.doclets packages?
 
 
E. Javadoc 1.1 Only
 
 
 
F. Doclets
 
       Doclets from Sun Microsystems

 

       Doclets from Third Parties
 
 
G. Taglets
 
       Taglets from Third Parties
 
 
H. Third Party Tools for Javadoc Tool
 
 
 
I. Third Party Tools for Java and Other Languages
 
Javadoc Tool Email

Using the Javadoc Tool


A1.  Where can I find the Javadoc tool and its documentation?

Javadoc tool - Included in the Java TM development kits. You can obtain the Javadoc tool by downloading the relevant JDK or SDK -- this is the only way to obtain the Javadoc tool:

 

The javadoc executable is in the bin directory.

Javadoc Tool Documentation - This documentation is contained in the Java 2 SDK Documentation, which you can browse here or download separately. The "Javadoc Tool Reference Doc" mentioned below is the central reference to the Javadoc tool and is similar to Unix "man pages". It describes how to set up and run the Javadoc tool, with examples, and contains a reference guide to the tags and options.

 

  Javadoc 5: Browse Javadoc 5.0 Tool Docs   Download as part of
JDK 5 docs
    Shortcut to Javadoc Tool Reference Doc (Solaris)
Shortcut to  Javadoc Tool Reference Doc (Windows)
  Javadoc 1.4: Browse Javadoc 1.4 Tool Docs   Download as part of
Java 2 SDK v1.4 docs
    Shortcut to Javadoc Tool Reference Doc (Solaris)
Shortcut to  Javadoc Tool Reference Doc (Windows)
 
  Javadoc 1.3: Browse Javadoc 1.3 Tool Docs   Download as part of
Java 2 SDK v1.3 docs
    Shortcut to Javadoc Tool Reference Doc (Windows)
 
  Javadoc 1.2: Browse Javadoc 1.2 Tool Docs   Download as part of
Java 2 SDK v1.2 docs
     Shortcut to Javadoc Tool Reference Doc (Solaris)
Shortcut to Javadoc Tool Reference Doc (Win32)
 
  Javadoc 1.1: Javadoc Tool Reference Doc (Solaris)
Javadoc Tool Reference Doc (Windows)		   (Single web page --
just use "Save As" to download)

Javadoc Tool Home Page has links to all documentation and related information on the Javadoc tool, including proposed Javadoc tags.

  A2.  How do I write Javadoc doc comments and tags?

To get details on how to write Javadoc tags and documentation comments, this is the best place at Sun to start: If your doc comments comprise an API specification, you might find this document useful:
  • Requirements for Writing API Specifications - Standard requirements used when writing the Java 2 Platform Specification. It can be useful whether you are writing API specifications in source file documentation comments or in other formats. It covers requirements for packages, classes, interfaces, fields and methods to satisfy testable assertions.

     

A3.  How do I run Javadoc?

There are two ways to run Javadoc -- on classes and on packages. The examples at the end of the Javadoc Tool Reference Doc describes both ways: Javadoc 1.1 has some important bugs, so if using that version, it is imperative to read the Javadoc 1.1 Only section of this FAQ. Also, Javadoc uses parts of the Java Compiler (javac) to parse through the source code. It is therefore simplest if you run Javadoc on the .java source files in the same directory hierarchy as they are in when you compile.

Once you've run Javadoc and want to view the generated HTML, the topmost page is named index.html (or packages.html in Javadoc 1.1).

 

A4.  How do I run Javadoc from within a Java application?

Starting with version 1.4.0, Javadoc has a programmatic interface in the form of an execute method. See Programmatic interface to Javadoc. 
your_method() {
    // your code
    String[] javadocargs = { "-d", "docs", 
                             "-sourcepath", "/home/user/src",
                             "java.applet" }; 
    com.sun.tools.javadoc.Main.execute(javadocargs); 
    // your code
}

For Javadoc 1.2.x and later, you can call main: 

your_method() {
    // your code
    String[] javadocargs = { "-d", "docs",
                             "-sourcepath", "/home/user/src",
                             "java.applet" };
    com.sun.tools.javadoc.Main.main(javadocargs);
    // your code
}

The disadvantages of calling main are: (1) It can only be called once per run -- for 1.2.x or 1.3.x, use java.lang.Runtime.exec("javadoc ...") if more than one call is needed, (2) it exits using Systme.exit(), which exits the entire program, and (3) an exit code is not returned.

For Javadoc 1.1.x, drop com (above) and instead use sun.tools.javadoc.Main.main(javadocargs);.

 

A5.  How can I tell which version of Javadoc I'm running?

Javadoc does not actually have a version number contained anywhere in its executable or classes ( tools.jar). By convention, we use the same version number for Javadoc as the JDK or SDK is it located in. Therefore, Java 2 SDK v1.2.2 contains Javadoc version 1.2.2.

To find the Javadoc version, simply find the version of the java executable by executing " javadoc -J-version".

Javadoc 1.2.2 gives this result:

   C:\> javadoc -J-version
   java version "1.2.2"
   Classic VM (build JDK-1.2.2-W, green threads, sunwjit)
The letter "W" is the internal build letter.

Javadoc 1.2 gives this result:

   C:\> javadoc -J-version
   java version "1.2"
   Classic VM (build JDK-1.2-V, green threads, sunwjit)

Javadoc 1.1.8 gives something like this result:

   C:\> javadoc -J-version
   java version "1.1.8"
To get the actual build letter for 1.1, use " -J-fullversion": 
   C:\> javadoc -J-fullversion
   java full version "JDK1.1.8M"

A6.  How do I write a shell script or batch file to run Javadoc?

Typing a javadoc command on the command line is burdensome and error-prone, especially if you use many options. You can move part of the command into files in two different ways:
  • Use the @file option to place the package or source filenames in a separate file.

     

  • On Windows, here is a Windows shell script. Save it to disk (in our example we call it run-javadoc.bat), then run it ( run-javadoc.bat).

     

  • On Solaris, write a shell script to hold the entire command, save it to a file, make the file executable, then run it. For example, here is a Solaris shell script. Save it to disk (in our example we call it run-javadoc), make it executable ( chmod a+x run-javadoc), then run it ( run-javadoc).
NOTE - On Solaris, it is very important to make sure the backslash continuation character ( \) is the last character on any line, not followed by spaces. If it is followed by a space, javadoc will stop execution and display a misleading error message saying " No package, class, or source file found named ." and will implicate the next option on the command line. For example, in the example shell script above, if a space appears at the end of " -d docs \ ", then javadoc will not execute the next option -use. This would be the error message: 
   % run-javadoc-SOLARIS
   javadoc: No package, class, or source file found named  .
   1 error
   run-javadoc-SOLARIS: -use: execute permission denied
A7.   I'm planning to upgrade to a newer version of Javadoc and am wondering what kinds of problems I might encounter?
Please read the 1.4 possible incompatibilities and 1.2 possible incompatibilities of What's New in Javadoc.

Javadoc 1.2 and later versions have been through a much more rigorous design and testing program than 1.1, and have proven to be much more reliable and robust. We have also been careful to write each verison Javadoc to be compatible with documentation comments written for previous versions of Javadoc. However, there may be a few cases where old documentation comments may not "work" the same when compiled with earlier versions. Please let us know of any other incompatibilites you run across.

A8.   Is there an easy way to print the many pages generated from Javadoc, such as PDF? Sun currently provides the API docs only in HTML, which is not easily printable.
Which route you go depends on whether you (1) have the source files and are willing to re-generate the documentation, or (2) simply want to print the HTML files (perhaps by converting them first to PDF).
  • The following two doclets require that you have the source files and convert those doc comments to PDF.

    PDF Doclet - Someone has written a PDF Doclet that converts doc comments in source files to a PDF document. We have not tried it, so cannot vouch for it. Please let us know your experience with it. As we understand it, the styles are fixed.

    MIF Doclet - If you want high quality and have the source code (containing the doc comments), and FrameMaker, and are willing to re-generate the documentation, you can use the MIF Doclet to convert to PDF (or PS) and print directly to a printer with a single command. You have a lot of flexibility to change the styles however you want.

     

  • The following programs convert the HTML files to Postscript or PDF.

    HTMLDOC . - Probably the simplest way (but not necessarily free) is to use HTMLDOC. A user has written in to say it's a great program for converting the javadoc-html to a nice postscript- or pdf-document. It runs on Windows and Unix, and there is a free demo Windows version which seems to be fully functional except cannot be run from the command line (for batch processing or providing conversions from a webserver).

    html2ps - Otherwise, the easiest way to print the documentation that we have found is to convert the documentation to PostScript using html2ps and then print that. (If you know of a good way of printing many HTML pages, please let us know.)

    Jan Kärrman has written a freely available program html2ps which batch-converts files to PostScript for easy printing or conversion to PDF. We have used it only on Solaris. It is fast and works great. If you find that it works on Windows, please let us know. The earlier versions use alternate text rather than printing images.

    Setup
    html2ps converts HTML files to PS for easy printing. 
      
                                                 http://www.tdb.uu.se/~jan/html2ps.html
    This directory contains the html2ps program, a readme file and a man page.
    Running html2ps on HTML files generated from Javadoc 1.2
    Since the HTML files are in different directories, you must include the package names on the command line, or concatenate the HTML files together before running html2ps. For the java.applet package, you would cd to the root api docs directory and run: 
    % html2ps *.html java/applet/*.html java/applet/class-use/*.html index-files/*.html 
          > apidocs.ps
    Running html2ps on HTML files generated from Javadoc 1.1
    Since the HTML files are all in one directory, you can run a simple command: 
    % html2ps *.html > apidocs.ps
    However, this causes classes to be printed one right after another, rather than having classes begin at the top of each page.
    Notes
    Page Order - If the above steps don't give you the pages in the order you want:
    1. At the beginning of each HTML file put an HTML comment: <!--NewPage-->
      (not necessary for Javadoc 1.2, since it automatically does this for you).
    2. Concatenate the HTML files together in the order you want them printed.
    3. Run html2ps on the huge concatenated file.
    The <!--NewPage--> comment ensures that each new HTML page will begin on a new physical page when printed. Scripts that performs steps 1 and 2 have been written by Francine Le Peintre, Gerard Sookahet and Xavier Outhier, and are available at:

    GIF Images - While html2ps does not handle GIFs, it does the next best thing, by substituting the alternate text for the GIF. Thus, it works great on the Java API generated from javadoc, which contains alternate text for its heading and bullet images.

    No Navigation Bar - If you don't want the navigation bar to appear at the top and bottom of each page, use the -nonavbar option when running javadoc.

    About html2ps
    Author: Jan Kärrman
    Dept. of Scientific Computing, Uppsala University, Sweden
    e-mail: [email protected]

    html2ps is a Perl script that is freely available. It works great and the author Jan is very responsive. html2ps supports a number of options.

A9.  Can I incrementally build a document from different runs of Javadoc?

Basically no, but there is a link feature that may provide what you need. First of all, Javadoc generates one and only one document each time you run it. It cannot modify or directly incorporate results from previous runs of Javadoc. However, it can link to results from previous runs. Here are these two cases:
  • Incremental Build - If you want to run Javadoc on package p1 and separately run Javadoc on package p2, integrating them into a single document with one overview page and one index page, this is not currently possible. We call this incremental build and are considering it for a future release.

     

  • Linking Documents - However, anytime you run Javadoc, you can use the -link or -linkoffline options to make it link to pre-existing documents generated from Javadoc. For example, since every class inherits from java.lang.Object, you can link to that class on our website if you'd like. All that is required is that those exisiting documents contain a file named package-list that lists the packages at that location. (Javadoc 1.2 and later versions automatically generate this file, located in the document's root directory, which also holds index.html.) When Javadoc encounters a package not specified on the command line, it will look in the specified package-list files for that package and link to it.

     

  • Inheriting Comments from J2SE - Your code can also automatically inherit comments from interfaces and classes in the J2SE. You can do this by unzipping the src.zip file that ships with the SDK (it does not contain all source files, however), and add its path to -sourcepath. When javadoc runs on your code, it will load the doc comments from those source files as needed. For example, if a class in your code implements java.lang.Comparable, the compareTo(Object) method you implement will inherit the doc comment from java.lang.Comparable.

A10. I'm using -link or -linkoffline but some of my external links do not show up. Why is this?

NOTE: See the related FAQ Why do I get the warning "Class or Package not found in @see tag" or "reference not found"?

NOTE: In 1.4.2 we have removed the import limitation described below by allowing links to any fully-qualified class pointed to with the -link option. For the related bug fix, see: 4662658: With -link, all @see/@link tags should create links to excluded classes

First ensure that the arguments to -link or -linkoffline are correct, and check that the package-list file exists at the location you expect it. You can check the latter by viewing it in a browser -- for example, the package list for the Java 2 Platform, Standard Edition, v1.4 API Specification is at: package-list .

If the above does not apply, it is still possible for a link to not appear due to a limitation in Javadoc. For a link to an external referenced class to actually appear, the class must be referenced in a particular way:

  • In 1.2.x and 1.3.x, it must be referenced explicitly by name in either a declaration or an import statement.
  • In 1.4.x, the rules have been relaxed slightly -- it must be referenced by a declaration or any kind of import statement (by wildcard, explicitly by name, or automatically for java.lang.*).
Note that it is not sufficient for it to be referenced in the body of a method. The most common workaround is described below.

If you are using Javadoc 1.2.2, if the above does not apply, and if @see and {@link} links are broken, then check with a  -link bug in Javadoc 1.2.2 .

Workaround - The most innocuous workaround is to import the class explicitly, by name:

   import java.io.File; // workaround to enable @see/@link hyperlink
The wildcard import statement import java.io.* works starting with 1.4.0. We strongly recommmend you add a comment similar to the one shown above to the right of the import statement, so the reason for the import statement can be understood, and can be removed if the Javadoc limitation is removed.

This limitation is further described at How a Class Must Be Referenced for a Link to Appear

A11. Is there a way to redirect links between multiple independently-built HTML Javadoc trees after installing them from independent products into arbitrary locations?

Let's state the question a different way. Let's say a user downloads the JDK and its javadoc-generated API documentation (set A). Next, the user downloads and installs a third-party product with its Javadoc-generated API documentation (set B) in a user-defined location. They would like the references from set B to point to set A.

Currently, Javadoc can create links from set B to set A (using "Linking Documents" in the previous question) but they must be specified at Javadoc build time, and can only be either absolute (using http:// or file:/) or relative, but can't use an environment variable that the user sets to redirect the links.

This limitation is inherent in HTML, which does not allow environment variables in links. Some possible solutions or workarounds that we are aware of are:

  • Use relative links with -link or -linkoffline and require documentation set B to be located relative to set A (On Solaris, these can be non-relative locations provided you use a symlink to perform the redirect.)
  • Write a script to change the hard-coded links in set B to the required hard-coded links
  • Replace the hard-coded links with a programmable link (Javascript? Applet tag? Object tag?) that could perform a redirect at runtime. We have not pursued this solution.
Someday when browser source is XML rather than HTML, dynamic redirects may be possible.
A12.   How does your implementation of Javadoc work?
Javadoc requires and relies on the java compiler to do its job. The first thing it does is call part of javac to compile the code, keeping the declarations and doc comments but discarding the implementation. It builds a parse tree and then generates the HTML from that.

In fact, javadoc will run on .java source files that are purely stub files with no method bodies. This means you can run Javadoc in the earliest stages of design, while you are writing the API but have not yet implemented it. Stub files are also a possible format for translating doc comments into other natural languages (French, German, Japanese, etc.).

Relying on the compiler ensures that the HTML output corresponds exactly with the actual implementation. For example, the compiler creates default versions of constructors that are not present in the source code. If Javadoc did not use the Java compiler, it would be difficult to handle these special cases.

 

A13.   Can I run javadoc on source files from other languages, such as C, C++ or VisualBasic?
No. Javadoc runs only on Java source code. See the previous question for the explanation. However, other vendors have worked on such documentation tools. They are listed at the bottom of this page.
A14.   How can I create custom Javadoc tags?
Javadoc 1.4 solves this problem with the -tag option to create simple tags and the -taglet option for complex tags (tags with more than one argument, or that require special HTML formatting on output).

To do this in earlier versions of Javadoc, it will take some creative programming on your part. You can start by looking at the example at How can I modify the standard doclet.

We have published a list of proposed tags. In this list you will notice a proposed tag @exclude for preventing parts of API from being documented. We have not developed a doclet containing such a tag (although our MIF doclet provides a way of excluding classes). We will publish doclets on this website that we have created or that others have created and want published.

One developer has created a custom tag @inverse to keep tracks of bi-directional links in the Java code generated by a CASE tool. For instance: 

class Owner {
   /**
    * my dogs
    * @inverse myOwner
    */
   Dog[] dogs;
}

class Dog {
   /**
    * my master
    * @inverse dogs
    */
   Owner myOwner;
}

The @inverse tag will allow the UML CASE tool to reverse the two fields 'dogs' and 'myOwner' as only one UML association instead of two, which is the default when no information is provided about the coupling between the two fields. ( Didier Simoneau)
A15.   Where can I find code examples for the Java API?
While we do not include many code examples in the Java API documentation, we do currently provide thousands of examples separately, for virtually all Java 1.1 API -- practically every class, interface, method, field and constructor -- from The Java Class Libraries: An Annotated Reference , by Patrick Chan and Rosanna Lee. While this book is not on-line, its examples are available for download at:

We also provide examples in the Java Tutorial, which is a programmer's guide to Java.

The earlier version Java 1.0 examples are also available at Java 1.0 code examples for java.applet, java.lang, java.util, java.io, java.net and java.awt

 

A16.   How can I exclude or skip certain public members or classes from being documented?
Occasionally you might need to make a class or method public so that it can be accessible from other packages, not because you want it to be part of the public API. Having these methods appear in the documentation merely confuses application developers.

There is currently no Javadoc option to hide, exclude or suppress public members from the javadoc-generated documentation.

Several options are available:

  • Excluding source files - You can pass into javadoc only the source filenames for all classes you want to document, and exclude those you want to omit. Notice this has the granularity of files, not classes. Therefore, if you exclude a source file that contains nested classes, they would also be excluded. (You can put the list of classes in a command line argument file rather than directly on the command line.) The default Javadoc offers no way to omit classes when passing in package names on the command line.
  • Excluding individual classes - You can use the Exclude Doclet. This has finer granularity (class rather than source file) than the previous option, and would be more natural to use because you explicitly list in a file the files you want to exclude.
  • Excluding classes, methods and fields - The yDoc Doclet has this capability, where you mark items with an exclusion tag in the source code. In addition, anyone is welcome to extend the Exclude Doclet above for methods and fields -- we'd be happy to publish it and add your name to the credits.

We are considering @exclude as a proposed tag for excluding members.

 

A17.   How would I create a makefile for documenting arbitrarily large libraries?
One of our developers, John Visosky, has donated a generic batch file and makefile for running javadoc on Windows. Please see Running Javadoc for Large Java Libraries.
A18.  May I see the slides presented at the JavaOne Javadoc Birds-of-a-Feather session?
Once at the first page, click on the Java coffee cup logo to go forward to the next slide, click at the top of the left-hand purple vertical stripe to go backward, and click in between those two spots to start over.
A19.  How do I generate documentation for packages that contain a package.html file but no java files?
Technically, that's currently not possible -- however, there is a practical workaround, where you include a package-private "placeholder" class in that package. So long as you don't use either the -private or -package option, the class will never appear in your documentation. 
  /**  
   * Exists only to enable package.html to be included in javadoc
   */
  class Placeholder {
  }

This is being tracked by Bug 4492654 We hope to remove this restriction.

Troubleshooting: Bugs, Errors and Warnings


B1.   What bugs are in Javadoc?
There are several places to look for reports of Javadoc bugs and feature requests:
  • This FAQ - For Javadoc 1.1 and 1.2, the most commonly encountered bugs are listed in this FAQ, along with workarounds where possible.

     

  • Release Notes - Some major known bugs for 1.4 are listed in its 1.4 Release Notes. (Nothing about Javadoc bugs is mentioned in the 1.2 or 1.3 Release Notes.)

     

  • What's New in Javadoc - Each release of the Java 2 SDK includes a list of changes to the Javadoc tool, which lists some of the important bugs fixed in that particular release; see What's New in Javadoc 1.4, 1.3, 1.2.2 and 1.2.

 

B2.   How do I submit bugs and feature requests?
When submitting a bug, be prepared to describe the steps and supply the source files needed to reproduce the bug (or do the best you can). We welcome your bug reports. If you have trouble with this bug submission process, please email us directly.
  1. Go to Report a Bug or Feature Request. Scroll to the bottom, check the checkbox and click "Start a New Report".

     

  2. Scroll down to "Start a Report". In the "Product/Category" pop-up, choose:
    Java 2 Platform Standard Edition, JRE/SDK (J2SE 1.4.x, 5.0)

     

  3. In the "Subcategory" pop-up menu, choose:
    Java API Documentation Generator Tool (javadoc)
    This subcategory is for bugs and features in any part of Javadoc tool -- the javadoc tool front end, standard doclet, Doclet API, Taglet API, or doclet toolkit in the JDK. For other doclets, see "Custom Doclet Bugs" below.

    NOTE - When choose an operating system, don't choose "Generic/Other", as it won't let you submit a bug (oddly).

     

Custom Doclet Bugs - You can also submit bugs against custom doclets such as the MIF Doclet, DocCheck Doclet, Localization Doclet, Exclude Doclet (any bug the standard doclet). In step 2 above, these have their own category under "Other Technologies" named "Custom Doclets for the Javadoc Tool"
B3.   How do I redirect error messages to a file?
In Windows NT/2000/XP and in Bourne (sh) and Korn (ksh) shells, you can redirect the standard message stream by using the ">" operator, and redirect the error messages stream by using the "2>" operator. For example, to redirect the standard messages to log.std and the error messages to log.err: 
   C:> javadoc -d docs java.lang >log.std 2>log.err
You may find it much more useful to redirect both streams to the same file, then search through the log file for the string "warning" or "error". (This is easier for Javadoc 1.3 and earlier, because the filename being processed appears in the standard output rather than the error output. However, starting with 1.4, the filename now appears on the same line as the error message.) For example: 
   C:> javadoc -d docs java.lang >javadoc.log 2>&1
You can redirect standard and error messages in C shell (csh) and T shell (tcsh) by using ">&", such as: 
   C:> javadoc -d docs java.lang >&javadoc.log

The MS-DOS shell in Windows 95/98/ME does not allow redirection of steams. You must use a shell that does, such as Cygwin or MKS.

B4.   I just can't get Javadoc to work on my entire source code; what do you suggest?
Here are some ideas. Basically, start small and work up:
  • Unset your classpath ( Solaris, Windows). If you're using Javadoc 1.1, make sure your API does not contain underscore or other characters outside of A-Z, a-z, 0-9 and period (.).
  • Try running javadoc on a single source file just to see if your setup is correct. For class MyClass in mypackage, it should generate a class file named "mypackage.MyClass.html" (for 1.1) or "mypackage\MyClass.html" (for 1.2) containing documentation for the class, plus a class hierarchy "tree.html" containing that one class, and an index "AllNames.html" (for 1.1) or "index-all.html" (for 1.2, without -splitindex) or "index-1.html" (for 1.2 with -splitindex) containing the members of that class. In Javadoc 1.1, the links to bullet and heading images will all be broken links unless you copy the images directory to where your HTML files are located (as described elsewhere in this FAQ).
  • Then try running javadoc on a single package, which will also generate a package file "Package-mypackage.html" (for 1.1) or "package-summary.html" (for 1.2). Source files should be in directories with the same names as the packages. Thus, the file MyClass.java should be in a directory called "mypackage".
  • If that succeeds, then try it on multiple packages.
B5.   I run out of memory -- how much is needed, exactly how do you at Java Software call Javadoc, and how long does it take?
Javadoc does take a lot of memory because (unlike javac) it must simultaneously load all the classes being documented, plus any that are referenced (such as superclasses and superinterfaces). Javadoc 1.1.x uses 40 MB of memory to generate the JDK 1.1.x documentation (22 packages). Javadoc 1.2 requires 120 MB of memory to generate the JDK 1.2 documentation (55 packages), which takes 8 minutes on an Ultra Enterprise with 512 MB of memory. Generating docs for all our public classes including sun.* (129 packages) requires 200 MB and takes 15 minutes on that same machine.

The javadoc 1.1.x command is shown with the -J-mx40m option below. Also, there is a bug in JDK 1.1.2 (fixed in 1.2), where the "ms" value must be smaller than (not equal to) the "mx" value. Without showing the complexity of environment variables and paths, the following is effectively the command that we run on the JDK 1.1 source code: 

javadoc -J-ms39m -J-mx40m \
             -classpath /usr/latest/build/solaris/classes \
             -d /usr/latest/build/doc/api \
             -sourcepath /usr/latest/src/share/classes:/tmp/javadoc \
             java.io java.lang java.lang.reflect java.util java.util.zip \
             java.awt java.awt.datatransfer java.awt.event \
             java.awt.image java.net java.applet \
             java.sql java.rmi java.rmi.registry java.rmi.server \
             java.security java.security.acl sun.tools.debug \
             java.text java.math java.beans \
             java.rmi.dgc java.security.interfaces

Fortunately, there are easier ways to run Javadoc without using the -classpath and -sourcepath options. See the Javadoc reference page.

For javadoc 1.2, this is the command we run (in a Solaris 'make' file) on the JDK 1.2 source code: 

 
                    
javadoc     -J-Xms120m -J-Xmx120m               \
            -splitIndex                         \
            -title $(JAVADOCTITLE)              \
            -header $(JAVADOCHEADER)            \
            -footer $(JAVADOCHEADER)            \
            -bottom $(JAVADOCBOTTOM)            \
            -d docs/api                         \
            -sourcepath ../src/share/classes/   \
            $(COREPKGS)

JAVADOCTITLE  = 'Java<sup><font size="-2">TM</font></sup> Platform 1.2 Beta 4 API Specification'

JAVADOCHEADER = '<b>Java Platform 1.2</b><br><font size="-1">Beta 4</font>'

JAVADOCBOTTOM = '<font size="-1">Java is a trademark of Sun Microsystems,  Inc.</font>'

COREPKGS =  java.applet                   \
            java.awt                      \
            java.awt.color                \
            java.awt.datatransfer         \
            java.awt.dnd                  \
            java.awt.event                \
            java.awt.font                 \
            java.awt.geom                 \
              etc.

For an example using a make file, please see the makefile question.
B6.   Why aren't the memory flags (-J-m) recognized in Windows?
In JDK 1.1.x, 1.2 Beta 1 and 1.2 Beta 2 on Microsoft Windows, there is a bug in the Javadoc wrapper that prevents the -J flags from being passed on to the virtual machine. The symptom is that when you specify the -J option, it says "invalid flag", as follows: 
  C:\> javadoc -J-mx40m MyClass.java
  javadoc: invalid flag: -J-mx40m
  usage: javadoc flags* [class | package]*
        -sourcepath <path>  Colon-separated list of source-file directories
        -classpath <path>   Synonym for -sourcepath
        ...

Workaround - Switch to Javadoc 1.2 Beta3 or later (you can use the -1.1 switch to make it look like the 1.1 javadoc output with gray background and GIF images for headers). Otherwise, bypass the wrapper script in JDK 1.1.x by running the Main class (which contains a "main" method) in the sun.tools.javadoc package, assuming the destination directory is "C:\html": 
  C:\> java -mx40m sun.tools.javadoc.Main -d html MyClass.java

B7.   When I run javadoc on my source package, some of the links are not generated. For example, for methods that have parameters of type Object, those parameters have no link to documentation for the Object class.

In Javadoc 1.2 and later, use the -link or -linkoffline options to create links to external referenced classes. These are classes outside of the packages passed in to the javadoc command. Therefore, if you run javadoc only on your own, it will not provide links to java.lang.Object unless you include one of these two options.

Javadoc 1.1 does not have these options to generate links to external referenced classes. (Javadoc 1.0 does include links to classes outside of the packages being operated on, but that means those links would be potentially broken links.)

See the next question for a related bug.

Workaround - Use the -link or -linkoffline options, or include the package or class in the javadoc command that you run.

B8.   In Javadoc 1.2.2, when using @see or {@link} tags to external API, any links to methods, fields and constructors are missing.

 

I am calling javadoc with "-link #". If I link to a class in 1.2.2 it works, but not if I link to a member. With v1.3 both classes and members work! For example: 
       import javax.swing.tree.TreeModel;
  
       /**
        * This is an example with a link to the method 
        * {@link TreeModel#getChildCount(Object) getChildCount()}
        * and it doesn't work with JDK 1.2.2
        */

This is a known bug only in 1.2.2. In 1.2.2, the -link and -linkoffline options link only to packages, classes and interfaces but not to members. This bug is not present in either earlier (1.2.0) or later (1.3.0) versions.

Workaround - Use Javadoc 1.2.0 or 1.3.0 (also known as versions 1.2 and 1.3). These are the versions found in the Java 2 SDK versions 1.2.0 and 1.3.0, respectively.

B9.   Why do I get the warning "Class or Package not found in @see/@link tag" or "reference not found"?
NOTE: See the related FAQ I'm using -link or -linkoffline but some of my external links do not show up. Why is this?"

NOTE: In 1.4.2 we have removed the import limitation described below by allowing links to any fully-qualified class pointed to with the -link option. For the related bug fix, see: 4662658: With -link, all @see/@link tags should create links to excluded classes

When @see or {@link} refers to a Java name that is not referenced -- that is, not used anywhere in the implementation of the classes being documented -- javadoc cannot find it, and displays one of these warnings: 
javadoc: warning - Class or Package not found, in @see tag: xxx
warning - Tag @see: reference not found: java.util.List
warning - Tag @link: reference not found: java.util.List
The following source file Test.java generates a warning because JSplitPane is not referenced in either the declaration or in an import statement. 
       /**
        * @see JSplitPane
        */
       public class Test {
       }

When you run javadoc, you get a warning: 
 % javadoc Test.java
 javadoc: warning - Class or Package not found, in @see tag: JSplitPane
The follow generates the @see link properly, without warning. Only one of the import statements is needed, depending on the version of Javadoc you are using. The wildcard import javax.swing.* statement is sufficient in 1.4.x. The explicit import javax.swing.JSplitPane statement is required in 1.2.x and 1.3.x. 
       import javax.swing.*;           // 1.4 workaround to enable @see link 
       import javax.swing.JSplitPane;  // 1.2 and 1.3 workaround to enable @see link 

       /**
        * @see JSplitPane
        */
       public class Test {
       }

Workaround - Include a reference to the Java name you want to include, such as importing the class explicitly.

B10.   The class comments are missing from the generated docs, but are in the source code. I only get the doc comments for the methods, fields and constructors.

If the class-level doc comments are missing, a common mistake is putting the import statement between the doc comment and the class definition in the source file. There must not be any statements between the class doc comment and the class declaration. 
    /**
     * This is the class comment for the class Whatever.
     */

    import com.sun;   // MISTAKE - Important not to put statements here

    public class Whatever {
    }

SOLUTION - Move the import statement ahead of the class comment.
B11.   When I run javadoc, I get the following exception warning: "Method X declares that it throws class Y, but there is no corresponding @exception item." What does this message mean?
This warning message means that there is no description on the line that contains the @exception tag. The @exception line should look something like: 
   * @exception  ReceiverException  An exception thrown by the receiver.
You get the warning if there is a return immediately after the exception name (ReceiverException). If you put the description on the next line, for example, you get this warning.

Workaround - Insert a space after the exception name.

B12.   I copied all of my .java files from their package hierarchy into a single directory so it would be easier to run javadoc on them, but it doesn't work. I get the message "Couldn't find <classname>"?
If your classes do not all belong to the unnamed package, you must put them in directories named after the packages. Do not put all .java files into the same directory (even if they will compile that way). For example, files belonging to java.awt and java.awt.swing must be in these directories: 
         DIRECTORIES 

           java
             |
             |
            awt
             | 
             +----------+
             |          |
           swing     *.java    (java.awt source files)
             | 
             +----------+
                        |
                    *.java     (java.awt.swing source files)

It is normally not possible for javadoc to run successfully when classes from different packages are in the same directory, because of certain dependencies between classes. Also, it's worthy to note that because javadoc calls parts of the java compiler to parse through the source code, it will not run on source code that is not compilable.
B13.   I am documenting 33 packages and added a new package to my javadoc command but this created a "No source files" error.
There is a limit to the number of characters Windows allows on the command line, about 1000 characters. A hint is that the error message lists a package name that is truncated. If the last package name is "com.mypackage", the error message might look like: 
   Warning: No source files for package com.mypackaC:\project\src
Notice the end of the line is corrupted: com.mypackaC:\project\src. This same problem can occur in Javadoc 1.1 or 1.2.

Workaround - In 1.2 or later you can use the command line argument file feature which allows arguments of any length to be placed in a file:

  javadoc @args
This is not implemented prior to 1.2 Beta4, so if using Javadoc 1.1, you must switch to Javadoc 1.2 or later, or run Javadoc on Solaris which has no such length limit (allows at least 10,000 characters).
B14.   I get the error "Class xxx already defined"
Problem #1 - This command:

javadoc ca.mcgill.sable.sablecc ca.mcgill.sable.sablecc.lexer

produced this error message: 

Loading source files for package ca.mcgill.sable.sablecc...
Loading source files for package ca.mcgill.sable.sablecc.lexer...
.\ca\mcgill\sable\sablecc\lexer\Lexer.java:17: 
                      Class ca.mcgill.sable.sablecc.lexer.Lexer already defined 
in ca/mcgill/sable/sablecc/lexer/Lexer.java.
public final class Lexer
                   ^
.\ca\mcgill\sable\sablecc\lexer\LexerException.java:10: 
                      Class ca.mcgill.sable.sablecc.lexer.LexerException already defined 
in ca/mcgill/sable/sablecc/lexer/LexerException.java.
public class LexerException extends Exception
             ^
2 errors

When running Javadoc on each package separately, it works ok. When combining them, Javadoc complains about every class in the second package. Am I doing something wrong, or can javadoc just not handle more than one package?

Solution #1 -

Your CLASSPATH includes both the jar file for the classes being documented and the un-jarred source files, so Javadoc thought there were duplicate definitions, but, oddly, only when you run Javadoc with more than one package name. The solution is to remove the jar file from the CLASSPATH. Note that you should be using SOURCEPATH to specify the path to the source files, anyway.

Problem #2 -

Someone else wrote in to say they get this error message "Class xxx already defined" when they comment out a class definition. If the whole class definition is commented, then error will be generated on class1, class2 and class3 (if they are already loaded by javadoc). 

package some.package;

import some.class1;
import some.class2;
import some.class3;

/*
public class SupClass {

    public void method1() {}

}
*/

Solution #2 -

The solution is: Do not comment out the class definition.

B15.   I get the errors "FileNotFoundException" and "Fatal Exception"
Problem - A user encountered the above errors when he tried to build the Javadoc documentation for a package called config. (Solaris operating system, Javadoc 1.2.1) 
% javadoc -d htm -sourcepath /home/project config

Loading source files for package config...
java.io.FileNotFoundException
        at sun.tools.javac.BatchEnvironment.parseFile(Compiled Code)
        at com.sun.tools.javadoc.Main.parseSourcePackage(Compiled Code)
        at com.sun.tools.javadoc.Main.initInner(Compiled Code)
        at com.sun.tools.javadoc.Main.init(Compiled Code)
        at com.sun.tools.javadoc.Main.main(Compiled Code)
javadoc: fatal exception
1 error

One symptom was that when he ran javadoc in the directory config and built the documentation for all classes (rather than for the package), there was no error. 
 % cd config
 % javadoc -d ../htm -classpath /home/project *.java
He didn't have a problem with any other package.

Solution - After a lot of sleuthing, he found a (hidden) file called:

    .#CreateConfig.java
in the config directory. After removing this file, it worked.

Moral of the Story - Look for stray .java source files that don't belong to the package.

B16.   Using Javadoc 1.4.1, I get an InvocationTargetException when I set the classpath.
Using Javadoc 1.4.1, I require that the classpath contain j2ee.jar (for the servlet library), but everytime I add that to the javadoc command, it returns the InvocationTargetException below. 
javadoc -classpath c:\j2sdkee1.3.1\lib\j2ee.jar -d ..\docs\ *.java

Constructing Javadoc information...
Standard Doclet version 1.4.1

Generating ..\docs\constant-values.html...
Building tree for all the packages and classes...
Building index for all the packages and classes...
Generating ..\docs\overview-tree.html...
Generating ..\docs\index-all.html...
...
Generating ..\docs\AADSHomeServlet.html...
javadoc: In doclet class com.sun.tools.doclets.standard.Standard, method start
has thrown an exception  
                     java.lang.reflect.InvocationTargetException
java.lang.NullPointerException
at java.util.zip.ZipFile.getInputStream(ZipFile.java:184)
at com.sun.tools.javadoc.PackageDocImpl.documentation(PackageDocImpl.jav
a:71)
at com.sun.tools.javadoc.DocImpl.comment(DocImpl.java:74)

Solution - Upgrade to Javadoc 1.4.2. Javadoc 1.4.1 has a bug where it tries to read package.html from the jar file without checking if it is really in there. This bug has been fixed in 1.4.2 as 4697040: javadoc is reporting errors when classpath jar files have package.html files.

If you must use 1.4.1, and are forced to put that jar file on the classpath, then open the jar file and put a valid package.html file at the package directory being documented, then jar it back up. For example, if documenting com.package1, then make sure the jar file contains com/package1/package.html.

FYI, the InvocationTargetException is just a wrapper for all exceptions thrown as a result of method invocation -- in this case, the start method. For instance methods, the "target" is an object, and for class methods, the "target" is a class.

B17.   Why do I get so many @serial warnings, including warnings about private fields (when I'm not using the -private options)?
There is currently no way to turn off the @serial tag warnings. A future maintenance release will turn the warnings off by default and will only be enabled when you provide a command line option (such as -serialwarn) to javadoc. You can safely ignore the warnings but you cannot turn them off. We can only suggest filtering the warnings out for now.

Any non-static and non-transient field of a Serializable class is considered a serializable field. Any field is serializable, regardless of its access type ( public, private or protected). Thus, private Serializable fields require a javadoc comment that includes an @serial tag. Requiring the @serial tag to be added to a default serializable field's doc comment carries the requirement of adding this tag to private fields.

For more information, see Why does the javadoc standard doclet generate many warnings about missing @serial and/or @serialData tags?, which also covers the question "Why do I see javadoc warnings stating that I am missing @serial tags for private fields if I am not running javadoc with the -private switch?". Also see @serial tag.

Customizing the Javadoc Tool


C1.   How can I modify the standard doclet to produce links to source code from the API documentation?
NOTE - Javadoc 1.4 solves this problem with the -linksource option that provides links to HTML versions of the source code.

NOTE - The following example was written for Javadoc 1.2. The standard doclet code has changed enough in 1.3 to make this example not work. If anyone has updated this example for 1.3 and would like to publish those changes, please notify us and we will post it here.

Let's say you want to change how the standard doclet works, such as adding a custom tag or modifying its generated HTML output. If possible, your first approach should be to subclass the standard doclet. By not changing any of the classes in the standard doclet, this provides an easier upgrade path when we release a new version of the standard doclet. However, sometimes it is not possible to get the behavior you want merely by subclassing -- in that case you would need to copy the standard doclet and modify its classes directly. It would be wise to rename the starting class for this doclet from Standard to something else, since it would no longer have the standard behavior. In either case, it would help to look at the examples we have for writing a custom doclet in the Doclet Overview.

The standard doclet source files are located in the com.sun.tools.doclets.standard package of the standard doclet. Then use the -doclet option to run the new doclet. The steps involved are as follows:

  1. Copy the source code files for the com.sun.tools.doclets.standard package into a working directory from Sun's standard doclet source code. You don't need to copy files from the com.sun.tools.doclets package.

     

  2. Remove the package declaration statement at the top of each source file in the copy. The package declaration statement looks like this: 
     package com.sun.tools.doclets.standard;
    This step is necessary so that the Javadoc tool can distinguish the classes in your modified doclet from those in the real com.sun.tools.doclets.standard package.

     

  3. You'll need to add or change a small amount code in these five source-code files: 
        
                         Standard.java
    
                         ClassWriter.java
    
                         HtmlStandardWriter.java
    
                         PackageWriter.java
    
                         PackageIndexWriter.java

    These links take you to source-code files that have already been modified. Search these files for lines containing the comment ' //new' to see what code has been added or changed.

     

  4. Compile the source code files. Note that even though the modified files of the doclet are no longer in the com.sun.tools.doclets.standard package, they still import the other package of the standard doclet, com.sun.tools.doclets and, of course, the doclet API in package com.sun.javadoc. The class files for these two imported packages are in the lib/tools.jar file of the Java 2 SDK software, so be sure to use the -classpath option of the javac command to put tools.jar on the class path when you compile.

     

  5. When the compilation is finished, you're ready to launch the doclet by using the command 
    javadoc -doclet Standard -sourcepath <path to source code files> ...

We could also have changed the name of the entry-class for the doclet to something other than Standard to underscore the fact that the doclet is no longer really the standard doclet. If you do this, make sure to change the name Standard where ever it appears in throughout the other files of the doclet.

This doclet gets the location of the source code from the -sourcepath command-line option. It places a "Source Code" subheading and a link to the underlying source code and near the top of each class-level API file. The link is a "file:" link, not an "http:" link and is absolute rather than relative. See this sample HTML output.

NOTE: For purposes of this demonstration, to make the links work from your browser, we hand-modified the URLs in the sample output from the file: form. The original URL for the link to the Applet.java source file, for example, was:
<a href="file:/home/username/ws/JDK1.2/src/share/classes/java/applet/Applet.java">
If you want javadoc to be able to point to source files that aren't at the location specified by the -sourcepath option, you can use the doclet API to invent a new command-line flag for telling Javadoc where the source files are located. You would do this if you want to distribute your documentation and source files to someone else, say, for customers to download from your website.
C2.   How can I change the colors and font sizes? The old gray background was a little easier on the eyes, and I don't like the new font sizes.
Starting with 1.2, Javadoc supports HTML style sheets. You can change the background color back to gray with two simple changes to one file, stylesheet.css (located at the root directory of the Javadoc HTML files):

To change the page background color, change this:

      body { background-color: #FFFFFF }
To:
      body { background-color: Silver }

To change the cell background color to silver, for example, change this:

      #TableRowColor { background: #FFFFFF } /* White */
To:
      #TableRowColor { background: Silver } /* Silver */

(In 1.2 beta releases prior to the final JDK 1.2 release, the previous statment starts with a period ".TableRowColor" rather than a hash symbol.)

To choose a smaller, sans-serif fonts for the left-hand frames, change this:

      #FrameItemFont { font-size: normal; font-family: normal }
To:
      #FrameItemFont { font-size: 10pt; font-family: helvetica arial sans-serif }

(In 1.2 beta releases prior to the final JDK 1.2 release, the previous statment starts with a period ".FrameItemFont" rather than a hash symbol.)

If you find better values for a smaller font size for the left-hand frames, please let us know so we can publish them. For more information, see: What's New in Javadoc 1.2.

C3.   How can I eliminate the HTML frames in the javadoc look?
Frames are entirely optional. If you don't want frames, don't use them. Simply turn frames off with a single click ("No Frames" near the top of any page). Or load the non-frame front page (overview-summary.html) instead of the frame set (index.html). All the navigation (except "All Classes") is available at the top of each web page. When you need to bookmark a page, you can always switch frames off with a single click and then switch them back on (although turning frames on always takes you to the front page).

 

C4.   How do I document Java platform classes using a later version of Javadoc?
This issue is a special case, of interest only to those documenting one verion of the Java platform classes, say 1.1, with a later "dot" version of Javadoc, say 1.2. This is normally of interest only to Sun employees, but is also of interest to those who want to know in detail how Javadoc searches for classes.

When running Javadoc 1.2 and attempting to document 1.1 core packages, Javadoc will (perhaps surprisingly) also document the 1.2 classes in those packages. The reason this happens is because (1) Javadoc is documenting these classes based on information extracted from their .class files (not source files), and (2) Javadoc has a default -bootclasspath where that points to rt.jar that contains these class files.

The workaround is to unset -bootclasspath, by setting its argument to the empty string. When you ask Javadoc to document the java.lang package, for example, it will document all classes in that package that are found in the bootclasspath, even if the source files for those classes are not present. Since all the 1.2 classes are present in bootclasspath, it documents all those classes. This is not a problem when documenting non-core packages, because those classes do not exist on bootclasspath. For more information on bootclasspath, see Finding Classes.

For example, if you run Javadoc 1.2 on the java.lang package for 1.1, it will also generate a page for java.lang.Character.Subset which is present only in 1.2.

The solution is to unset bootclasspath and point sourcepath to the 1.1 source files. Pointing -sourcepath to the source files ensures that Javadoc can find everything referenced by the classes being documented.

  % javadoc -bootclasspath "" -sourcepath [path_to_1.1_sources] java.lang
The double quotes are needed to tell the shell that the argument is empty. Here's an example with the real path for JDK 1.1.7: 
  % javadoc -bootclasspath "" -sourcepath
    /java/jdk/1.1.7/ws/MASTER/src/share/java:/java/jdk/1.1.7/ws/MASTER/src/share/sun
   java.lang
Note that the "sun" directory is included to prevent a slew of errors, since it is referenced. Using -sourcepath rather than -bootclasspath is also slower and uses more memory since all these referenced classes must be parsed.
C5.   How do I workaround the new restriction in 1.4 that HTML tags cannot be used around parameter names?
Prior to 1.4, the Javadoc tool support HTML around parameter names in a method comment: 
   /**
    * @param <I>values</I>  the value to get
    */
   public void setValue(int value) {
   }

Now that the standard doclet supports taglets, if a user wants all parameter names to be italic or bold, in the long run it would make more sense for them to write a taglet to do that, as it eliminates having to type HTML tags for every parameter. The the above comment would look like: 
   /**
    * @param values   the value to get
    */
   public void setValue(int value) {
   }

However, if users don't want to change existing source code, they can use this ParamTaglet which allows the use of HTML around parameter names. Put the compiled class in a directory named <path>/com/sun/tools/doclets/standard/tags and then use these options to javadoc: 
-tagletpath <path>
-taglet com.sun.tools.doclets.standard.tags.ParamTaglet
This taglet will override the built-in ParamTaglet.

Developing with the Javadoc Tool


D1.  Where can I find the source code for the Javadoc tool and standard doclet?
The source code for the Javadoc tool (including the standard doclet) is contained in the source release for the J2SE Development Kit (JDK), available at:

 

D2. Where can I find the com.sun.javadoc and com.sun.tools.doclets packages?

The class files are contained in lib/tools.jar of the Java 2 SDK, Standard Edition that you download. To see its location in the SDK, look at:

Java 2 SDK File Structure

For Javadoc 1.1, the Javadoc classes were located in packages sun.tools.javadoc in classes.zip (doclets did not exist in 1.1).

Javadoc 1.1 Only

Doclets


Doclets From Sun Microsystems

  • MIF Doclet.
MIF Doclet Home Page contains information about the MIF Doclet. This doclet is being developed by the Javadoc team. It enables you to generate files that you can open in FrameMaker and save as Postscript, PDF, RTF, Word or WordPerfect documents. This is not a supported product -- we have developed it for internal use and have made it available as-is, with no warranty or promise to fix bugs.
  • DocCheck Doclet.
DocCheck is a doclet in the Sun Doc Check Utilities that checks doc comments in source files and generates a report listing the errors and irregularities it finds.
  • Localization Doclets.
We have translated the doc comments and API documentation into other languages, for example Japanese API docs (To view the Japanese characters, in Netscape, choose View > Character Set > Japanese (Auto-Detect).) Full translation involves translating both the doc comments and "labels". Labels are static text that includes headings, subheadings, the navigation bar, standard links, generic phrases, and help. Examples include the words "Overview", "Package", "Class", "Member Summary", "Subclasses", and "Methods inherited by".
  • We translate the doc comments with a pair of doclets: (1) a pre-processing doclet that extracts the text from the source files into comment files that are more easily translated, and (2) a post-processing modification to the standard HTML doclet that Javadoc uses to import the translated text from the comment files into the generated documentation.
  • We translate the "labels"by translating the file com/sun/tools/javadoc/resources/standard.properties found in lib/tools.jar. For example, the Japanese file is com/sun/tools/javadoc/resources/standard_ja.properties. Note that if you are translating into Japanese, this translated file is already provided in the Java 2 SDK, Standard Edition.
Full translation should also include translating any text or images in the doc-files directories, if any. If you have a need or interest in such a translation process, please contact us. We have no plans for releasing these doclets, but may do so on an experimental level if there is enough demand to do so.
  • Exclude Doclet.
Exclude Doclet is a very simple wrapper program that enables you to exclude from the generated documentation any public or protected classes (or packages) that you specify. It takes a list of classes in a file and removes them from the RootDoc before delegating execution to the standard doclet. Also see How can I exclude or skip certain public members or classes from being documented?.

Doclets From Third Parties

  • Doclet.com - website of third-party doclets
Doclet.com contains links to documentation, articles, tools, and third-party doclets.
  • Dynamic HTML Doclet.
Dynamic Javadoc (called DJavadoc) generates API documentation that has dynamic hide/show capabilities. You can view the Java 2 Platform API Specifications now available for testing on the web. Please have a look and send any comments you may have to Erik Berglund. This version makes use of DHTML-features available in Internet Explorer 4 or later (Netscape 4 does not have enough of these DHTML features) to enable the reader to create more-focused or less-focused views of the documentation. In the current version the user may also create a more focused navigation view of the whole package-structure in a bookmark-like fashion.
  • Simple RTF Doclet.
Nicolas Zin has published a simple RTF doclet for generating RTF from doc comments. You can download the RTF doclet. This works with Javadoc 1.2 or later. The generated files were tested to work with WinWord 97. A README.txt file in contained in the download bundle describes how to run it and welcomes bug fixes.
  • TexiDoclet. - Useful for GNU Emacs and GNU/Linux
TexiDoclet generates API documentation in TexInfo (.texi) or Info format (.info). It includes a context-sensitive documentation lookup system for the GNU Emacs editor.
  • LaTeX2e Doclet.
C2 Technologies, Inc. has created a LaTeX2e doclet to aid in the creation of printed documentation. Please send email to Gregg Wonderly
  • DocLint Doclet - Checks doc comments
DocLint is a doclet that checks doc comments for missing comments and other documentation discrepancies.
  • JDiff Doclet - Generates difference between two sets of API.
JDiff Doclet generates an HTML report of all the packages, classes, constructors, methods, and fields, including their documentation, which have been removed, added or changed when two APIs are compared. Great for reporting what APIs have changed between two releases of your product.
  • Bouvard Doclet - Generates documentation for the Pecuchet browser for more effective exploration.
Bouvard Doclet generates documentation in a format for the Pecuchet browser expressly designed for more effective exploration. This doclet and browser allow you to:
  • graphically depict the relationships among classes and interfaces, using user's selection to focus on a reduced set of elements
  • rapidly find a class, interface, field, constructor or method by simply typing its partial name while the global index automatically positions itself.
  • filter the visible elements according to their type and attributes
  • organize information with flexibility, choosing the preferred combination of lists, graphics and text
  • DocBook Doclet - Generates DocBook SGML or XML documentation.
DocBook Doclet is a doclet that allows you to generate reference handbooks from doc comments for printed documentation. It supports:
  • DocBook SGML 3.1 and 4.1
  • DocBook XML 4.1.2
  • Overview Comment Files
  • Package Comment Files
Please send comments to Michael Fuchs.
  • yDoc Doclet - Lets you exclude elements, generate UML diagrams and define custom tags using XML
yDoc is a doclet that let's you:
  • exclude classes, fields, and methods by adding an exclusion tag (y.exclude), and also allows for sophisticated custom filter criteria
  • define custom tags via an XML based mechanism
  • automatically generate and incorporate UML class diagrams in your API
The UML generation is yDoc's main purpose and will be constantly improved and enhanced.
  • Classdoc - Not a doclet, but a program that lets you generate API documentation from class files
See classdoc
  • Ashkelon - An online API reference tool providing a single, fully cross-referenced, searchable database repository.

    Ashkelon - An online reference tool for api documentation. Ashkelon is javadoc taken to the next step of being able to reference multiple APIs (>100,000 methods) in a single, fully cross-referenced and searchable database repository. It contains a doclet for getting data into the database.

    Ashkelon is used to publish a number of Jakarta APIs on the site dbdoc.org.

  • JUnit Doclet - Helps developers with generating and maintaining JUnit tests.

    JUnit Doclet - Incremental behaviour keeps modified code when regenerating. Assists with refactorings (no tests get lost when renaming, moving, etc.). See this article explaining the use of JUnit: " Testing Without Excuses - Diligent but routine pieces of work for JUnit should be the computer's task." (33K, PDF)

  • PDF Doclet - Generates PDF from doc comments in source files

    PDF Doclet - Someone has written a PDF Doclet that converts doc comments in source files to a PDF document. We have not tried it, so cannot vouch for it. Please let us know your experience with it. As we understand it, the styles are fixed.

     

  • Bookmark Doclet - Generates HTML files for import into Netscape or Mozilla bookmarks

    Bookmark Doclet has been released by Bright Ring Software LLC under the GNU Public License. This doclet does not generate API documentation; instead, it generates HTML files that can be imported into Netscape or Mozilla bookmarks. The bookmarks refer to online Javadoc documentation generated by the standard doclet. Their multiple levels mirror the package structure of the underlying code. For an example, see Bookmark file for JDK 1.4.1.

  • Auriga Doclet - Generate API documents in fo, pdf, postscript, pcl and svg format

    The doclet has options for specifying a header/footer and a cover page. It also has options to enable/disable a table of contents, pdf outline, an index (at the end of book). The look and feel of the output can be controlled using css. Also, since it uses xsl fo for formatting, the output the output can be customized further by overriding the xsl.

    Sample output (pdf)

    The doclet is hosted at sourceforge.net: Auriga Doclet Project Page

  • DocFlextor for Javadoc - Template-driven doclet and template designer

    DocFlextor for Javadoc is a template-driven doclet and template designer. This tool allows you to quickly design new doclets in the form of templates and generate with them Java API documentation and other sorts of output in HTML, RTF and TXT formats. The HTML output may be both single-file and framed documentation. TXT is a plain text that can be use to generate whatever else (XML files, for instance). There is also a freeware version called DocFlextor Doclet. This is only the doclet without Template Designer. The supplied templates are embedded as resources. This may be also interesting for users because among other things it provides a high quality RTF generator for the Javadoc tool.

  • XHTML Doclet - Generates valid XHTML 1.0 document pages with flexible CSS styling

    XHTML Doclet is a doclet for use with Javadoc, intended as a modern alternative to the Standard doclet. It creates valid XHTML 1.0 Transitional markup and provides better hooks for more flexible CSS styling. The focus is on creating intelligent document structure without any inline styling, resulting in greater freedom to change the appearance of all the files, either site-wide or for certain types of pages.

Taglets


Taglets From Third Parties

  • @ru.k2s.example Taglet
@ru.k2s.example Taglet - Enables the insertion of code examples. The first sentence of the tag's text is a lead-in sentence; the rest is an example that is displayed in code font and enclosed with a border. Examples are allowed everywhere from the overview down to the fields and methods. Inline {@link} tags are processed by the taglet too. Taglet is free for any use.
  • Taglet Collection
The Taglet Collection is set of general pupose taglets for use with the JavaDoc tool. It provides a standard set of new tags and allows to create new ones by configuration or using simple Java interfaces. Tested with J2SE 1.4, 1.5 and JavaSE 1.6.
  •  
  • (your taglet here)

Third Party Tools for Javadoc Tool


  • Scripts to recurse over source directories.
Javadoc will not recurse over source directories for you. The following scripts are for developers who are documenting many packages and want javadoc to run on the source files in all subdirectories of a given "root" directory.

Platform-Independent Recursion

Here is a platform-independent solution to recurse directories, building a list of package names for javadoc. It works by recursing down through the directory names you pass in, looking for any directories that contain *.java filenames. In other words, it assumes a package is any directory that contains a .java file (which is not always a good assumption, obviously).

 

  1. Download the source file GetAllSubPackages.java. Compile it: 
    C:>  
                   javac GetAllSubPackages.java
  2. Build a file containing a listing of package names, where each rootdir is a directory where package directories are rooted: 
    C:>  
                   java GetAllSubPackages packages.txt rootdir1 rootdir2 rootdirN

    For example, if your package is com.myCompany.myPackage, located at C:\source\com\myCompany\myPackage:

    C:>  
                   java GetAllSubPackages packages.txt C:\source

     

  3. Then use @packages.txt for your source packages: 
    C:>  
                   javadoc -d doc @packages.txt
The above code was submitted by James Schriever ([email protected]), Sterling Wentworth Corporation.

The following is a solution for Solaris makefiles.

Solaris Only
The following script also builds a list of package names.

  1. In your 'make' file, build the list of package names with the statement:

    PACKAGES:sh = find subpackage -type d | sed "s,/,.,g"

    where subpackage is the top part of the package name, such as java from java.applet. For example,

    PACKAGES:sh = find java -type d | sed "s,/,.,g"

    would find all subdirectories as follows, and change the directory separators ( /) to dots ( .): 
    java
java/applet
java/applet/doc-files
java/lang
java/lang/reflect

    Notice it includes any "doc-files" directories, which you would need to filter out.

     

  2. Then run the javadoc statement in the makefile: 
                        javadoc -d doc $(PACKAGES)
This suggestion was submitted by Cal Cluff at Illgen Simulation Technologies, Inc.

Windows Only

The following works on Windows NT, but has the limitation that it generates a list of source files rather than package names. Because it does not process whole packages, it will not process the package.html files, nor will it generate lists of packages in the output.

 

    for /r %1 in (*.java) do javadoc %1
  • Utility for writing doc comments: Doc+.
Doc+ is a full featured authoring and editing tool for Javadoc comments. Doc+ is to Javadoc what HTML editors are to web page design. It allows the developer to write Javadoc comments for classes, fields and methods present in the code. The developer can scan and work with multiple source files concurrently. The developer has the ability to quickly and easily create, remove and edit Javadoc tags. Doc+ provides a preview of the HTML that will be generated by Javadoc and a source code viewer. Advanced features such as autofill, templates, comment conversion, and a concept called PackageMaps make documenting a large project a matter of minutes. Custom tag feature ensures support for any new Javadoc tags. A bonus feature is integrated JavaHelp for quick reference. Developed by WoodenChair Software Corp. (Not to be confused with Doc++.)
  • Tool that simplifies the process of writing doc comments: DocWiz.
DocWiz allows you to easily add Javadoc comments to your source code, without tedious hand-formatting. It also protects you from editing the source code. When you open a Java source file in DocWiz, it provides a list of all the fields, methods and classes defined in that file. Click on any of these code elements to display an editable fill-in form containing the comments. After editing the comments, save the file to incorporate the changes into the file.
  • 2-frame interface with package/class/method access to javadoc-generated API docs.
2-Frame Interface with package/class/method access is a small set of files that change the interface to the API docs from 3 frames to 2 frames. The left-hand frame first shows a list of all package names; when you click on a package, the package list is replaced with all class names in that package; when you click on a class, the class list is replaced with all method names in that package. Very nice design. From Dave Hunter.
  • Search facility added as a front end to Java API documentation.
API Search. Are you tired of browsing the Java API with Netscape's "Find..." ? Then this applet may be of assistance. Just type in a string and the applet tries to match it to all methods and variables in the Java API. The results are then displayed in a listbox. Clicking on an entry shows the documentation of the entry as generated by Javadoc.

A word of warning: API Search offers several versions. Depending on the version you choose, the loading time may be well over one minute as a JAR file with the compiled index will be loaded.

  • Source code formatting tool for transforming sources written in Java to your own coding style.
Jindent is a source code formatting tool for the Java language. Jindent supports numerous options and switches to transform Java sources to your very own coding style including the Java Coding Style proposed by Sun. Furthermore, Jindent is able to generate javadoc templates.
  • Editor that supports Sun's Java coding style: Emacs with cc-mode.
The Emacs editor ( GNU Emacs, XEmacs) supports Sun's coding standard (such as indentation) for Java. Both versions of Emacs support this standard through the built-in use of the cc-mode package (also available separately at http://www.python.org/emacs/cc-mode).

If you know of other editors, please let us know and we will add them to this list.

  • Tool for checking the quality of doc comments: iDoc.
iDoc is a free quality assurance (QA) tool for doc comments in Java source code. It supports developers in keeping source code doc comments up to date, in synch with the code itself and compliant with Java guidelines. iDoc analyzes the doc comments and code of classes, interfaces, methods and instance variables. iDoc is fully compatible with javadoc and complements it by providing several features that javadoc does not provide. (As of August 1999, it has not been updated for Javadoc 1.2.)
  • Development environment with class browsers/editors: teikade.
teikade is an environment to assist developers in writing programs using the Java language. The system includes a class browser and editor, hierarchy browser, a compilation frame, an execution frame, and tracing of references.
  • Program that writes HTML documentation for OMG IDL source code: idldoc.
idldoc is a program that accepts OMG IDL source code and writes HTML documentation for the contained definitions. It can be used to provide Web-accessible documentation for CORBA-compliant distributed objects. See the sample pages generated by idldoc. This program is completely unrelated to javadoc and doclets, except that the design of its source code documentation comments and generated HTML pages resemble that of javadoc.
  • Swing interface to Javadoc 1.1
Swing interface to Javadoc 1.1 (click on "Download"). Must also install Swing for JDK 1.1 and AltaBeans. To see the interface, view the interface here. Send email to Stéphane Nicolas.
  • Giant Java tree automated release and distribution system (AutoRad).
The AutoRad system leverages the ability to write doclets for Javadoc 1.2, defining custom javadoc tags for GJT packages that specify the release of the package, the packages that the package depends on, as well as the release tags of those dependent packages.
  • UML diagrams integrated with Javadoc pages.
JVISION creates UML class diagrams from Java code or Java source to document existing Java applets and applications and for learning other people's code.

The new JVISION Documentor beta adds a project and diagram manager integrated with Javadoc from Sun. Create an instant web site documenting an entire project. Navigate through a tree hierarchy of diagrams and click on a class to see Javadoc HTML.

  • Tool for generating formated Javadoc comments: CommentMaster
CommentMaster is a tool designed to help developers comment source code written in the Java language. It recursively reads files defined in a tree and formats comments to be compliant with the Javadoc standard. Users are able to define custom templates for missing comments. CommentMaster will comment files, classes, methods, variables, and inner classes. With an intuitive project wizard, it allows developers to fix comments in a matter of few minutes and work with multiple projects at the same time. Developed by Objectsoft, Inc
  • Tool for editing Javadoc comments using a word processor-like view: XMLmind XML Editor.
XMLmind XML Editor - Contains a Javadoc plug-in; the intended audience for this Javadoc plug-in is Java programmers and Javadoc writers. With XMLmind XML Editor and this plug-in, it becomes possible to edit the Javadoc comments contained in a Java file using a word processor-like view. Writing Javadoc this way is less tedious (no manual formatting of comment lines) and is no longer error-prone (DTD-directed editing).
  • Tool for reformatting the code and inserting javadoc comments: JRefactory Pretty Printer.
JRefactory Pretty Printer - A pretty printer for Java. It reads a java file or a directory structure containing java files. It reformats the code and inserts javadoc comments where they are missing.

This version takes a look at the name of the method. If the method is a setter or getter, it takes an intelligent stab at filling in the javadoc comments, based on the name of the method, the class, and whether the method is static or not.

If the method is named "run" or it appears to be the main program, the javadoc comments are also generated appropriately. The exact words in the default descriptions for all methods are located in the pretty.settings file.

  • Tool for generating API documentation from .class files: Classdoc.
classdoc - This program enables you to generate API documentation from non-obscured .class files. Of course, the documentation will consist only of declarations, not comments, because .class files do not contain doc comments. It parses Java .class files implements the Doclet API so that any doclet can be used to generate output. By default, the Standard Doclet is used to generate API documentation in HTML. By using other doclets, you can generate other formats such as PDF, DocBook, or LaTeX2e.

This program answers a need that the -Xclasses option would satisfy in Javadoc 1.4.2. However, this non-standard option will be subject to change or removal from release-to-release.

  • Tool for inserting doc comments into Java source code: Auto Commentator.
ACTOS Auto Commentator for Java - A program that helps you to make documentation comments for your Java sources. It is more easily and quickly than by hand. It inserts documentation comments for methods and members into your Java sources. How does it work? Auto Commentator scans your Java sources and calculates statistics about all parameters and exceptions in sources. You should only specify description of equal params and exceptions. After that Auto Commentator inserts your descriptions as part of documentation comment in the Java source files.

Third Party Tools for Java and Other Languages


Tools that generate documentation from Java, C, C++, VB, Assembly and other languages. Here are a few -- if you know of others, please let us know so we can add them to this list.

DISCLAIMER: We do not test, endorse or guarantee the utility or fitness of third-party software. Use at your own risk.

 

  • CDOC Professional is a set of automated tools for Windows3.1/Win95/WinNT, OS/2, and DOS. They analyze existing C, C++, or Java programs and generate caller/called tree diagrams, class hierarchy trees, class inheritence/containment reports, identifier cross-references, reformat source or action-diagram listings, count code/comments and calculate path cyclomatic complexity, generate/insert/update function comment blocks.

     

  • Surveyor V4.5 - Transform your C++ code into a web site that everyone in your workgroup can browse. Create class hierarchy charts showing all inheritance relationships. Quickly and easily document your projects without code modifications. Jump straight from your browser to related code in your favorite editor.

     

  • DocJet - A tool for generating documentation from comments in source code. Version 3.0 works with Java, Visual Basic, C, C++, and MS IDL. There is a full-featured demonstration version available for download. You will probably also be interested in AltHelp, a plug-in for VB and VisualStudio which can display DocJet-generated HTML just like the built-in documentation.

     

  • Autoduck - A Windows 95/NT console utility for documenting C, C++, Java, VB and Assembly. Outputs only to Rich Text Format (RTF). (No link at this time)

     

  • Doc++ - A Unix utility for documenting C, C++ and Java. Outputs to LaTeX and HTML. Runs on IRIX, Linux and SunOSLinux, Solaris, AIX, HP/UX, IRIX, OSF, Unixware, Windows '95, '98 and NT. DOC++ was originally written by Roland Wunderling and Malte Zöckler, was further improved by Michael Meeks, and is currently maintained by Dragos Acostachioaie. (Not to be confused with Doc+.)

     

  • Doxygen - a documentation system for C, C++ and IDL. It can generate an on-line class browser (in HTML) and/or an off-line reference manual (in Latex) from a set of documented source files. There is also support for generating man pages and for converting the generated output into Postscript, hyperlinked PDF or compressed HTML. The documentation is extracted directly from the sources. Doxygen is developed on Linux, but it runs on most other UNIX flavors as well. An executable for Windows 9x/NT is also available.

     

  • Object Outline for software written in C and C++, generates HTML, RTF and WinHelp documentation. By Bumble Bee Software.

     

  • PERCEPTS for software written in C++, generates HTML. Uses templates for custom output formats.

     

  • grdoc for documenting C, C++ and Fortran.

     

  • HeaderDoc - A doc generator Tool for C, C++ and Objective C from Apple.

     

  • Doc-O-Matic - Generates source code documentation, online help and user manuals from one source in various formats: HTML Help, Windows Help, browser-based help and double-side printable PDF. It has an integrated editor that supports Javadoc tags. You can author comments in Javadoc style that can be inserted into Java (or C++, VB.NET, Delphi) source code. The current version does not support Javadoc inline tags, such as {@link}.

Contacting the Javadoc Team

We'd love to hear from you. Please send us questions that you would like added to this FAQ.

We publish some of the Javadoc feature requests at Bug Parade at the Java Developer Connection website. (Registration is free.) Search for "javadoc" or whatever you might want.

If you are writing to the above email address to ask about problems running javadoc, you must provide the following information:

  • The version of javadoc (type " java -version", not " javadoc -version").
  • The exact javadoc command you are executing, with all options.
  • The fully-qualified name of the package or class you are trying to document
    (such as com.mycompany.testpackage or com.mycompany.testpackage.testclass.java).
  • The full path of the package(s) or class(es) you are running javadoc on. (If a class, include the .java filename). Such as C:\java\com\mycompany\testpackage or C:\java\com\mycompany\testpackage\*.java.
  • The full path of the current directory.
  • The value of CLASSPATH environment variable.
  • The error message.
Note: Please only submit questions and comments about the tool itself, including the standard doclet, and the format it generates. We cannot answer questions or comments about the content of the generated documentation. Please contact the documentation team to submit bugs or comments about the content as described.
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