javadoc - The Java API Documentation Generator

Generates HTML pages of API documentation from Java source files. This document contains JavadocTM examples for Sun Solaris.

CONTENTS

Reference Guide Running

Reference Guide

SYNOPSIS

javadoc [ options ] [ packagenames ] [ sourcefilenames ] [ -subpackages pkg1:pkg2:... ] [ @argfiles ]

Arguments can be in any order. See processing of Source Files for details on how the Javadoc tool determines which ".java" files to process.

options
Command-line options, as specified in this document. To see a typical use of javadoc options, see Real-World Example.
packagenames
A series of names of packages, separated by spaces, such as java.lang java.lang.reflect java.awt. You must separately specify each package you want to document. Wildcards are not allowed; use -subpackages for recursion. The Javadoc tool uses -sourcepath to look for these package names. See Example - Documenting One or More Packages
sourcefilenames
A series of source file names, separated by spaces, each of which can begin with a path and contain a wildcard such as asterisk (*). The Javadoc tool will process every file whose name ends with ".java", and whose name, when stripped of that suffix, is actually a legal class name (see Identifiers). Therefore, you can name files with dashes (such as X-Buffer), or other illegal characters, to prevent them from being documented. This is useful for test files and template files The path that precedes the source file name determines where javadoc will look for the file. (The Javadoc tool does not use -sourcepath to look for these source file names.) Relative paths are relative to the current directory, so passing in Button.java is identical to ./Button.java. A source file name with an absolute path and a wildcard, for example, is /home/src/java/awt/Graphics*.java. See Example - Documenting One or More Classes. You can also mix packagenames and sourcefilenames, as in Example - Documenting Both Packages and Classes
-subpackages pkg1:pkg2:...
Generates documentation from source files in the specified packages and recursively in their subpackages. An alternative to supplying packagenames or sourcefilenames.
@argfiles
One or more files that contain a list of Javadoc options, packagenames and sourcefilenames in any order. Wildcards (*) and -J options are not allowed in these files.

DESCRIPTION

The JavadocTM tool parses the declarations and documentation comments in a set of Java source files and produces a corresponding set of HTML pages describing (by default) the public and protected classes, nested classes (but not anonymous inner classes), interfaces, constructors, methods, and fields. You can use it to generate the API (Application Programming Interface) documentation or the implementation documentation for a set of source files.

You can run the Javadoc tool on entire packages, individual source files, or both. When documenting entire packages, you can either use -subpackages for traversing recursively down from a top-level directory, or pass in an explicit list of package names. When documenting individual source files, you pass in a list of source (.java) filenames. Examples are given at the end of this document. How Javadoc processes source files is covered next.

Processing of source files

The Javadoc tool processes files that end in ".java" plus other files described under Source Files. If you run the Javadoc tool by explicitly passing in individual source filenames, you can determine exactly which ".java" files are processed. However, that is not how most developers want to work, as it is simpler to pass in package names. The Javadoc tool can be run three ways without explicitly specifying the source filenames. You can (1) pass in package names, (2) use -subpackages, and (3) use wildcards with source filenames (*.java). In these cases, the Javadoc tool processes a ".java" file only if it fulfills all of the following requirements:

Processing of links - During a run, the Javadoc tool automatically adds cross-reference links to package, class and member names that are being documented as part of that run. Links appear in several places:

You can add hyperlinks to existing text for classes not included on the command line (but generated separately) by way of the -link and -linkoffline options.

Other processing details - The Javadoc tool produces one complete document each time it is run; it cannot do incremental builds -- that is, it cannot modify or directly incorporate results from previous runs of the Javadoc tool. However, it can link to results from other runs, as just mentioned.

As implemented, the Javadoc tool requires and relies on the java compiler to do its job. The Javadoc tool calls part of javac to compile the declarations, ignoring the member implementation. It builds a rich internal representation of the classes, including the class hierarchy, and "use" relationships, then generates the HTML from that. The Javadoc tool also picks up user-supplied documentation from documentation comments in the source code.

In fact, the Javadoc tool will run on .java source files that are pure stub files with no method bodies. This means you can write documentation comments and run the Javadoc tool in the earliest stages of design while creating the API, before writing the implementation.

Relying on the compiler ensures that the HTML output corresponds exactly with the actual implementation, which may rely on implicit, rather than explicit, source code. For example, the Javadoc tool documents default constructors (section 8.6.7 of Java Language Specification) that are present in the .class files but not in the source code.

In many cases, the Javadoc tool allows you to generate documentation for source files whose code is incomplete or erroneous. This is a benefit that enables you to generate documentation before all debugging and troubleshooting is done. For example, according to the Java Language Specification, a class that contains an abstract method should itself be declared abstract. The Javadoc tool does not check for this, and would proceed without a warning, whereas the javac compiler stops on this error. The Javadoc tool does do some primitive checking of doc comments. Use the DocCheck doclet to check the doc comments more thoroughly.

When the Javadoc tool builds its internal structure for the documentation, it loads all referenced classes. Because of this, the Javadoc tool must be able to find all referenced classes, whether bootstrap classes, extensions, or user classes. For more about this, see How Classes Are Found. Generally speaking, classes you create must either be loaded as an extension or in the Javadoc tool's class path.

Javadoc Doclets

You can customize the content and format of the Javadoc tool's output by using doclets. The Javadoc tool has a default "built-in" doclet, called the standard doclet, that generates HTML-formatted API documentation. You can modify or subclass the standard doclet, or write your own doclet to generate HTML, XML, MIF, RTF or whatever output format you'd like. Information about doclets and their use is at the following locations: When a custom doclet is not specified with the -doclet command line option, the Javadoc tool will use the default standard doclet. The javadoc tool has several command line options that are available regardless of which doclet is being used. The standard doclet adds a supplementary set of command line options. Both sets of options are described below in the options section.

Related Documentation and Doclets

Terminology

The terms documentation comment, doc comment, main description, tag, block tag, and in-line tag are described at Documentation Comments. These other terms have specific meanings within the context of the Javadoc tool:
generated document
The document generated by the javadoc tool from the doc comments in Java source code. The default generated document is in HTML and is created by the standard doclet.

name
A name of a program element written in the Java Language -- that is, the name of a package, class, interface, field, constructor or method. A name can be fully-qualified, such as java.lang.String.equals(java.lang.Object), or partially-qualified, such as equals(Object).

documented classes
The classes and interfaces for which detailed documentation is generated during a javadoc run. To be documented, the source files must be available, their source filenames or package names must be passed into the javadoc command, and they must not be filtered out by their access modifier (public, protected, package-private or private). We also refer to these as the classes included in the javadoc output, or the included classes.

included classes
Classes and interfaces whose details are documented during a run of the Javadoc tool. Same as documented classes.

excluded classes
Classes and interfaces whose details are not documented during a run of the Javadoc tool.

referenced classes
The classes and interfaces that are explicitly referred to in the definition (implementation) or doc comments of the documented classes and interfaces. Examples of references include return type, parameter type, cast type, extended class, implemented interface, imported classes, classes used in method bodies, @see, {@link}, {@linkplain}, and {@inheritDoc} tags. (Notice this definition has changed since 1.3.) When the Javadoc tool is run, it should load into memory all of the referenced classes in javadoc's bootclasspath and classpath. (The Javadoc tool prints a "Class not found" warning for referenced classes not found.) The Javadoc tool can derive enough information from the .class files to determine their existence and the fully-qualified names of their members.

external referenced classes
The referenced classes whose documentation is not being generated during a javadoc run. In other words, these classes are not passed into the Javadoc tool on the command line. Links in the generated documentation to those classes are said to be external references or external links. For example, if you run the Javadoc tool on only the java.awt package, then any class in java.lang, such as Object, is an external referenced class. External referenced classes can be linked to using the -link and -linkoffline options. An important property of an external referenced class is that its source comments are normally not available to the Javadoc run. In this case, these comments cannot be inherited.


SOURCE FILES

The Javadoc tool will generate output originating from four different types of "source" files: Java language source files for classes (.java), package comment files, overview comment files, and miscellaneous unprocessed files. This section also covers test files and template files that can also be in the source tree, but which you want to be sure not to document.

Class Source Code Files

Each class or interface and its members can have their own documentation comments, contained in a .java file. For more details about these doc comments, see Documentation Comments.

Package Comment Files

Each package can have its own documentation comment, contained in its own "source" file, that the Javadoc tool will merge into the package summary page that it generates. You typically include in this comment any documentation that applies to the entire package.

To create a package comment file, you must name it package.html and place it in the package directory in the source tree along with the .java files. The Javadoc tool will automatically look for this filename in this location. Notice that the filename is identical for all packages. For explicit details, see the example of package.html.

The content of the package comment file is one big documentation comment, written in HTML, like all other comments, with one exception: The documentation comment should not include the comment separators /** and */ or leading asterisks. When writing the comment, you should make the first sentence a summary about the package, and not put a title or any other text between <body> and the first sentence. You can include package tags; as with any documentation comment, all tags except {@link} must appear after the main description. If you add a @see tag in a package comment file, it must have a fully-qualified name.

When the Javadoc tool runs, it will automatically look for this file; if found, the Javadoc tool does the following:

Overview Comment File

Each application or set of packages that you are documenting can have its own overview documentation comment, kept in its own "source" file, that the Javadoc tool will merge into the overview page that it generates. You typically include in this comment any documentation that applies to the entire application or set of packages.

To create an overview comment file, you can name the file anything you want, typically overview.html and place it anywhere, typically at the top level of the source tree. Notice you can have multiple overview comment files for the same set of source files, in case you want to run javadoc multiple times on different sets of packages. For example, if the source files for the java.applet package are contained in /home/user/src/java/applet directory, you could create an overview comment file at /home/user/src/overview.html.

The content of the overview comment file is one big documentation comment, written in HTML, like the package comment file described previously. See that description for details. To re-iterate, when writing the comment, you should make the first sentence a summary about the application or set of packages, and not put a title or any other text between <body> and the first sentence. You can include overview tags; as with any documentation comment, all tags except in-line tags, such as {@link}, must appear after the main description. If you add a @see tag, it must have a fully-qualified name.

When you run the Javadoc tool, you specify the overview comment file name with the -overview option. The file is then processed similar to that of a package comment file.

Miscellaneous Unprocessed Files

You can also include in your source any miscellaneous files that you want the Javadoc tool to copy to the destination directory. These typically includes graphic files, example Java source (.java) and class (.class) files, and self-standing HTML files whose content would overwhelm the documentation comment of a normal Java source file.

To include unprocessed files, put them in a directory called doc-files which can be a subdirectory of any package directory that contains source files. You can have one such subdirectory for each package. You might include images, example code, source files, .class files, applets and HTML files. For example, if you want to include the image of a button button.gif in the java.awt.Button class documentation, you place that file in the /home/user/src/java/awt/doc-files/ directory. Notice the doc-files directory should not be located at /home/user/src/java/doc-files because java is not a package -- that is, it does not directly contain any source files.

All links to these unprocessed files must be hard-coded, because the Javadoc tool does not look at the files -- it simply copies the directory and all its contents to the destination. For example, the link in the Button.java doc comment might look like: 

    /**
     * This button looks like this: 
     * <img src="doc-files/Button.gif">
     */

Test Files and Template Files

Some developers have indicated they want to store test files and templates files in the source tree near their corresponding source files. That is, they would like to put them in the same directory, or a subdirectory, of those source files.

If you run the Javadoc tool by explicitly passing in individual source filenames, you can deliberately omit test and templates files and prevent them from being processed. However, if you are passing in package names or wildcards, you need to follow certain rules to ensure these test files and templates files are not processed.

Test files differ from template files in that the former are legal, compilable source files, while the latter are not, but may end with ".java".

Test files - Often developers want to put compilable, runnable test files for a given package in the same directory as the source files for that package. But they want the test files to belong to a package other than the source file package (such as the unnamed package), as defined by the package statement. In this scenario where source files are not explicitly specified, this will cause warnings or errors. You need to put such test files in a subdirectory. For example, if you want to add test files for source files in com.package1, put them in a directory: 

    com/package1/test-files/
The test files will be ignored by the Javadoc tool (though this warning might appear: "No source files for package com.package1.test-files").

If your test files contain doc comments, you can set up a separate run of the Javadoc tool to produce documentation of the test files by passing in source filenames with wildcards, such as com/package1/test-files/*.java.

Templates for source files - Template files have names that often end in ".java" and are not compilable. If you have a template for a source file that you want to keep in the source directory, you can name it with a dash (such as Buffer-Template.java), or any other illegal Java character, to prevent it from being processed. This relies on the fact that the Javadoc tool will only process source files whose name, when stripped of the ".java" suffix, is actually a legal class name (see Identifiers).


GENERATED FILES

By default, javadoc uses a standard doclet that generates HTML-formatted documentation. This doclet generates the following kinds of files (where each HTML "page" corresponds to a separate file). Note that javadoc generates files with two types of names: those named after classes/interfaces, and those that are not (such as package-summary.html). Files in the latter group contain hyphens to prevent filename conflicts with those in the former group.

Basic Content Pages

Cross-Reference Pages

Support Files

HTML Frames

The Javadoc tool will generate either two or three HTML frames, as shown in the figure below. It creates the minimum necessary number of frames by omitting the list of packages if there is only one package (or no packages). That is, when you pass a single package name or source files (*.java) belonging to a single package as arguments into the javadoc command, it will create only one frame (C) in the left-hand column -- the list of classes. When you pass into javadoc two or more package names, it creates a third frame (P) listing all packages, as well as an overview page (Detail). This overview page has the filename overview-summary.html. Thus, this file is created only if you pass in two or more package names. You can bypass frames by clicking on the "No Frames" link or entering at overview-summary.html.

If you are unfamiliar with HTML frames, you should be aware that frames can have focus for printing and scrolling. To give a frame focus, click on it. Then on many browsers the arrow keys and page keys will scroll that frame, and the print menu command will print it. 

              ------------                  ------------
              |C| Detail |                  |P| Detail |
              | |        |                  | |        |
              | |        |                  |-|        |
              | |        |                  |C|        |
              | |        |                  | |        |
              | |        |                  | |        |
              ------------                  ------------
             javadoc *.java           javadoc java.lang java.awt
Load one of the following two files as the starting page depending on whether you want HTML frames or not: Generated File Structure

The generated class and interface files are organized in the same directory hierarchy that Java source files and class files are organized. This structure is one directory per subpackage.

For example, the document generated for the class java.applet.Applet class would be located at java/applet/Applet.html. The file structure for the java.applet package follows, given that the destination directory is named apidocs. All files that contain the word "frame" appear in the upper-left or lower-left frames, as noted. All other HTML files appear in the right-hand frame.

NOTE - Directories are shown in bold. The asterisks (*) indicate the files and directories that are omitted when the arguments to javadoc are source filenames (*.java) rather than package names. Also when arguments are source filenames, package-list is created but is empty. The doc-files directory will not be created in the destination unless it exists in the source tree. 

apidocs                             Top directory
   index.html                       Initial page that sets up HTML frames
 * overview-summary.html            Lists all packages with first sentence summaries
   overview-tree.html               Lists class hierarchy for all packages
   deprecated-list.html             Lists deprecated API for all packages
   constant-values.html             Lists values of static fields for all packages
   serialized-form.html             Lists serialized form for all packages
 * overview-frame.html              Lists all packages, used in upper-left frame
   allclasses-frame.html            Lists all classes for all packages, used in lower-left frame
   help-doc.html                    Lists user help for how these pages are organized
   index-all.html                   Default index created without -splitindex option
   index-files                      Directory created with -splitindex option
       index-<number>.html          Index files created with -splitindex option
   package-list                     Lists package names, used only for resolving external refs
   stylesheet.css                   HTML style sheet for defining fonts, colors and positions
   java                             Package directory
       applet                       Subpackage directory
            Applet.html             Page for Applet class
            AppletContext.html      Page for AppletContext interface
            AppletStub.html         Page for AppletStub interface
            AudioClip.html          Page for AudioClip interface
          * package-summary.html    Lists classes with first sentence summaries for this package
          * package-frame.html      Lists classes in this package, used in lower left-hand frame
          * package-tree.html       Lists class hierarchy for this package
            package-use             Lists where this package is used
            doc-files               Directory holding image and example files
            class-use               Directory holding pages API is used
                Applet.html         Page for uses of Applet class
                AppletContext.html  Page for uses of AppletContext interface
                AppletStub.html     Page for uses of AppletStub interface
                AudioClip.html      Page for uses of AudioClip interface
   src-html                         Source code directory
       java                         Package directory
           applet                   Subpackage directory
                Applet.html         Page for Applet source code
                AppletContext.html  Page for AppletContext source code
                AppletStub.html     Page for AppletStub source code
                AudioClip.html      Page for AudioClip source code

Generated API Declarations

The Javadoc tool generates a declaration at the start of each class, interface, field, constructor, and method description for that API item. For example, the declaration for the Boolean class is:

public final class Boolean
extends Object
implements Serializable

and the declaration for the Boolean.valueOfmethod is:

public static Boolean valueOf(String s)

The Javadoc tool can include the modifiers public, protected, private, abstract, final, static, transient, and volatile, but not synchronized or native. These last two modifiers are considered implementation detail and not part of the API specification.

Rather than relying on the keyword synchronized, APIs should document their concurrency semantics in the comment's main description, as in "a single Enumeration cannot be used by multiple threads concurrently". The document should not describe how to achieve these semantics. As another example, while Hashtable should be thread-safe, there's no reason to specify that we achieve this by synchronizing all of its exported methods. We should reserve the right to synchronize internally at the bucket level, thus offering higher concurrency.

DOCUMENTATION COMMENTS

The original "Documentation Comment Specification" can be found under related documentation.

Commenting the Source Code

You can include documentation comments ("doc comments") in the source code, ahead of declarations for any class, interface, method, constructor, or field. You can also create doc comments for each package and another one for the overview, though their syntax is slightly different. Doc comments are also known informally as "Javadoc comments" (but this term violates its trademark usage). A doc comment consists of the characters between the characters /** that begin the comment and the characters */ that end it. Leading asterisks are allowed on each line and are described further below. The text in a comment can continue onto multiple lines. 

/**
 * This is the typical format of a simple documentation comment
 * that spans two lines.
 */
To save space you can put a comment on one line: 
/** This comment takes up only one line. */
Placement of comments - Documentation comments are recognized only when placed immediately before class, interface, constructor, method, or field declarations -- see the class example, method example, and field example. Documentation comments placed in the body of a method are ignored. Only one documentation comment per declaration statement is recognized by the Javadoc tool.

A common mistake is to put an import statement between the class comment and the class declaration. Avoid this, as the Javadoc tool will ignore the class comment. 

   /**
    * This is the class comment for the class Whatever.
    */

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

    public class Whatever {
    }
A doc comment is composed of a main description followed by a tag section - The main description begins after the starting delimiter /** and continues until the tag section. The tag section starts with the first block tag, which is defined by the first @ character that begins a line (ignoring leading asterisks, white space, and leading separator /**). It is possible to have a comment with only a tag section and no main description. The main description cannot continue after the tag section begins. The argument to a tag can span multiple lines. There can be any number of tags -- some types of tags can be repeated while others cannot. For example, this @see starts the tag section: 

/**
 * This sentence would hold the main description for this doc comment.
 * @see java.lang.Object
 */
Block tags and in-line tags - A tag is a special keyword within a doc comment that the Javadoc tool can process. There are two kinds of tags: block tags, which appear as @tag (also known as "standalone tags"), and in-line tags, which appear within curly braces, as {@tag}. To be interpreted, a block tag must appear at the beginning of a line, ignoring leading asterisks, white space, and separator (/**). This means you can use the @ character elsewhere in the text and it will not be interpreted as the start of a tag. If you want to start a line with the @ character and not have it be interpreted, use the HTML entity &#064;. Each block tag has associated text, which includes any text following the tag up to, but not including, either the next tag, or the end of the doc comment. This associated text can span multiple lines. An in-line tag is allowed and interpreted anywhere that text is allowed. The following example contains the block tag @deprecated and in-line tag {@link}. 

/**
 * @deprecated  As of JDK 1.1, replaced by {@link #setBounds(int,int,int,int)}
 */

Comments are written in HTML - The text must be written in HTML, in that they should use HTML entities and can use HTML tags. You can use whichever version of HTML your browser supports; we have written the standard doclet to generate HTML 3.2-compliant code elsewhere (outside of the documentation comments) with the inclusion of cascading style sheets and frames. (We preface each generated file with "HTML 4.0" because of the frame sets.)

For example, entities for the less-than (<) and greater-than (>) symbols should be written &lt; and &gt;. Likewise, the ampersand (&) should be written &amp;. The bold HTML tag <b> is shown in the following example.

Here is a doc comment: 

/**
 * This is a <b>doc</b> comment.
 * @see java.lang.Object
 */

Leading asterisks - When javadoc parses a doc comment, leading asterisk (*) characters on each line are discarded; blanks and tabs preceding the initial asterisk (*) characters are also discarded. Starting with 1.4, if you omit the leading asterisk on a line, the leading white space is no longer removed. This enables you to paste code examples directly into a doc comment inside a <PRE> tag, and its indentation will be honored. Spaces are generally interpreted by browsers more uniformly than tabs. Indentation is relative to the left margin (rather than the separator /** or <PRE> tag).

First sentence - The first sentence of each doc comment should be a summary sentence, containing a concise but complete description of the declared entity. This sentence ends at the first period that is followed by a blank, tab, or line terminator, or at the first block tag. The Javadoc tool copies this first sentence to the member summary at the top of the HTML page. See -breakiterator for a description of how we are planning in a future release to change the way the sentence break is determined.

Declaration with multiple fields - Java allows declaring multiple fields in a single statement, but this statement can have only one documentation comment, which is copied for all fields. Therefore if you want individual documentation comments for each field, you must declare each field in a separate statement. For example, the following documentation comment doesn't make sense written as a single declaration and would be better handled as two declarations: 

/** 
 * The horizontal and vertical distances of point (x,y)
 */
public int x, y;      // Avoid this
The Javadoc tool generates the following documentation from the above code: 
public int x
The horizontal and vertical distances of point (x,y) 
public int y
The horizontal and vertical distances of point (x,y)
Use header tags carefully - When writing documentation comments for members, it's best not to use HTML heading tags such as <H1> and <H2>, because the Javadoc tool creates an entire structured document and these structural tags might interfere with the formatting of the generated document. However, it is fine to use these headings in class and package comments to provide your own structure.

Automatic Copying of Method Comments

The Javadoc tool has the ability to copy or "inherit" method comments in classes and interfaces under the following two circumstances. Constructors, fields and nested classes do not inherit doc comments.

The source file for the inherited method need only be on the path specified by -sourcepath for the doc comment to actually be available to copy. Neither the class nor its package needs to be passed in on the command line. This contrasts with 1.3.x and earlier releases, where the class had to be a documented class

Inherit from classes and interfaces - Inheriting of comments occurs in all three possible cases of inheritance from classes and interfaces:

In the first two cases, for method overrides, the Javadoc tool generates a subheading "Overrides" in the documentation for the overriding method, with a link to the method it is overriding, whether or not the comment is inherited.

In the third case, when a method in a given class implements a method in an interface, the Javadoc tool generates a subheading "Specified by" in the documentation for the overriding method, with a link to the method it is implementing. This happens whether or not the comment is inherited.

Algorithm for Inheriting Method Comments - If a method does not have a doc comment, or has an {@inheritDoc} tag, the Javadoc tool searches for an applicable comment using the following algorithm, which is designed to find the most specific applicable doc comment, giving preference to interfaces over superclasses:

  1. Look in each directly implemented (or extended) interface in the order they appear following the word implements (or extends) in the method declaration. Use the first doc comment found for this method.
  2. If step 1 failed to find a doc comment, recursively apply this entire algorithm to each directly implemented (or extended) interface, in the same order they were examined in step 1.
  3. If step 2 failed to find a doc comment and this is a class other than Object (not an interface):
    1. If the superclass has a doc comment for this method, use it.
    2. If step 3a failed to find a doc comment, recursively apply this entire algorithm to the superclass.

JAVADOC TAGS

The Javadoc tool parses special tags when they are embedded within a Java doc comment. These doc tags enable you to autogenerate a complete, well-formatted API from your source code. The tags start with an "at" sign (@) and are case-sensitive -- they must be typed with the uppercase and lowercase letters as shown. A tag must start at the beginning of a line (after any leading spaces and an optional asterisk) or it is treated as normal text. By convention, tags with the same name are grouped together. For example, put all @see tags together.  

Tags come in two types:

For information about tags we might introduce in future releases, see Proposed Tags.

The current tags are:

Tag Introduced in JDK/SDK
@author 1.0
{@docRoot} 1.3
@deprecated 1.0
@exception 1.0
{@inheritDoc} 1.4
{@link} 1.2
{@linkplain} 1.4
@param 1.0
@return 1.0
@see 1.0
@serial 1.2
@serialData 1.2
@serialField 1.2
@since 1.1
@throws 1.2
{@value} 1.4
@version 1.0

For custom tags, see the -tag option.

@author  name-text
Adds an "Author" entry with the specified name-text to the generated docs when the -author option is used. A doc comment may contain multiple @author tags. You can specify one name per @author tag or multiple names per tag. In the former case, the Javadoc tool inserts a comma (,) and space between names. In the latter case, the entire text is simply copied to the generated document without being parsed. Therefore, you can use multiple names per line if you want a localized name separator other than comma.

For more details, see Where Tags Can Be Used and writing @author tags.

@deprecated  deprecated-text
Adds a comment indicating that this API should no longer be used (even though it may continue to work). The Javadoc tool moves the deprecated-text ahead of the main description, placing it in italics and preceding it with a bold warning: "Deprecated". This tag is valid in all doc comments: overview, package, class, interface, constructor, method and field.

The first sentence of deprecated-text should at least tell the user when the API was deprecated and what to use as a replacement. The Javadoc tool copies just the first sentence to the summary section and index. Subsequent sentences can also explain why it has been deprecated. You should include a {@link} tag (for Javadoc 1.2 or later) that points to the replacement API:

For more details, see writing @deprecated tags.

  • For Javadoc 1.2 and later, use a {@link} tag. This creates the link in-line, where you want it. For example: 
    /**
 * @deprecated  As of JDK 1.1, replaced by {@link #setBounds(int,int,int,int)}
 */
  • For Javadoc 1.1, the standard format is to create a @see tag (which cannot be in-line) for each @deprecated tag.

For more about deprecation, see The @deprecated tag.

{@docRoot}
Represents the relative path to the generated document's (destination) root directory from any generated page. It is useful when you want to include a file, such as a copyright page or company logo, that you want to reference from all generated pages. Linking to the copyright page from the bottom of each page is common.

This {@docRoot} tag can be used both on the command line and in a doc comment: This tag is valid in all doc comments: overview, package, class, interface, constructor, method and field, including the text portion of any tag (such as @return, @param and @deprecated).

  1. On the command line, where the header/footer/bottom are defined: 
       javadoc -bottom '<a href="{@docRoot}/copyright.html">Copyright</a>'
    NOTE - When using {@docRoot} this way in a make file, some makefile programs require special escaping for the brace {} characters. For example, the Inprise MAKE version 5.2 running on Windows requires double braces: {{@docRoot}}. It also requires double (rather than single) quotes to enclose arguments to options such as -bottom (with the quotes around the href argument omitted).

  2. In a doc comment: 
       /**
    * See the <a href="{@docRoot}/copyright.html">Copyright</a>.
    */
The reason this tag is needed is because the generated docs are in hierarchical directories, as deep as the number of subpackages. This expression: 
  <a href="{@docRoot}/copyright.html">
would resolve to: 
  <a href="../../copyright.html">      for java/lang/Object.java
and 
  <a href="../../../copyright.html">   for java/lang/ref/Reference.java

@exception  class-name  description
The @exception tag is a synonym for @throws.

{@inheritDoc} 
Note: This feature is broken in 1.4.0, but fixed in 1.4.1
Inherits (copies) documentation from the "nearest" inheritable class or implementable interface into the current doc comment at this tag's location. This allows you to write more general comments higher up the inheritance tree, and to write around the copied text.

This tag is valid only in these places in a doc comment:

  • In the main description block of a method. In this case, the main description is copied from a class or interface up the hierarchy.
  • In the text arguments of the @return, @param and @throws tags of a method. In this case, the tag text is copied from the corresponding tag up the hierarchy.

See Automatic Copying of Method Comments for a more precise description of how comments are found in the inheritance hierarchy. Note that if this tag is missing, the comment is or is not automatically inherited according to rules described in that section.

{@link  package.class#member  label}
Inserts an in-line link with visible text label that points to the documentation for the specified package, class or member name of a referenced class. This tag is valid in all doc comments: overview, package, class, interface, constructor, method and field, including the text portion of any tag (such as @return, @param and @deprecated).

This tag is very simliar to @see -- both require the same references and accept exactly the same syntax for package.class#member and label. The main difference is that {@link} generates an in-line link rather than placing the link in the "See Also" section. Also, the {@link} tag begins and ends with curly braces to separate it from the rest of the in-line text. If you need to use "}" inside the label, use the HTML entity notation &#125;

There is no limit to the number of {@link} tags allowed in a sentence. You can use this tag in the main description part of any documentation comment or in the text portion of any tag (such as @deprecated, @return or @param).

For example, here is a comment that refers to the getComponentAt(int, int) method: 

Use the {@link #getComponentAt(int, int) getComponentAt} method.
From this, the standard doclet would generate the following HTML (assuming it refers to another class in the same package): 
Use the <a href="Component.html#getComponentAt(int, int)">getComponentAt</a> method.
Which appears on the web page as: 
Use the getComponentAt method.
You can extend {@link} to link to classes not being documented by using the -link option.

For more details, see writing {@link} tags.

{@linkplain  package.class#member  label}
Identical to {@link}, except the link's label is displayed in plain text than code font. Useful when the label is plain text. Example: 
     Refer to {@linkplain add() the overridden method}.
This would display as:
Refer to the overridden method.
@param  parameter-name description
Adds a parameter to the "Parameters" section. The description may be continued on the next line. This tag is valid only in a doc comment for a method or constructor.

For more details, see writing @param tags.

@return  description
Adds a "Returns" section with the description text. This text should describe the return type and permissible range of values. This tag is valid only in a doc comment for a method.

For more details, see writing @return tags.

@see  reference
Adds a "See Also" heading with a link or text entry that points to reference. A doc comment may contain any number of @see tags, which are all grouped under the same heading. The @see tag has three variations; the third form below is the most common. This tag is valid in any doc comment: overview, package, class, interface, constructor, method or field. For inserting an in-line link within a sentence to a package, class or member, see {@link}.

@see "string"
Adds a text entry for string. No link is generated. The string is a book or other reference to information not available by URL. The Javadoc tool distinguishes this from the previous cases by looking for a double-quote (") as the first character. For example: 
     @see "The Java Programming Language"
This generates text such as:
See Also:
"The Java Programming Language"
@see <a href="URL#value">label</a>
Adds a link as defined by URL#value. The URL#value is a relative or absolute URL. The Javadoc tool distinguishes this from other cases by looking for a less-than symbol (<) as the first character. For example: 
     @see <a href="spec.html#section">Java Spec</a>
This generates a link such as:
See Also:
Java Spec
@see  package.class#member  label
Adds a link, with visible text label, that points to the documentation for the specified name in the Java Language that is referenced. The label is optional; if omitted, the name appears instead as the visible text, suitably shortened -- see How a name is displayed. Use -noqualifier to globally remove the package name from this visible text. Use the label when you want the visible text to be different from the auto-generated visible text.

Only in version 1.2, just the name but not the label would automatically appear in <code> HTML tags, Starting with 1.2.2, the <code> is always included around the visible text, whether or not a label is used.

  • package.class#member is any valid program element name that is referenced -- a package, class, interface, constructor, method or field name -- except that the character ahead of the member name should be a hash character (#). The class represents any top-level or nested class or interface. The member represents any constructor, method or field (not a nested class or interface). If this name is in the documented classes, the Javadoc tool will automatically create a link to it. To create links to external referenced classes, use the -link option. Use either of the other two @see forms for referring to documentation of a name that does not belong to a referenced class. This argument is described at greater length below under Specifying a Name.

  • label is optional text that is visible as the link's label. The label can contain whitespace. If label is omitted, then package.class.member will appear, suitably shortened relative to the current class and package -- see How a name is displayed.

  • A space is the delimiter between package.class#member and label. A space inside parentheses does not indicate the start of a label, so spaces may be used between parameters in a method.

Example - In this example, an @see tag (in the Character class) refers to the equals method in the String class. The tag includes both arguments: the name "String#equals(Object)" and the label "equals". 

 /**
  * @see String#equals(Object) equals
  */
The standard doclet produces HTML something like this: 
<dl>
<dt><b>See Also:</b>
<dd><a href="../../java/lang/String#equals(java.lang.Object)"><code>equals<code></a>
</dl>
Which looks something like this in a browser, where the label is the visible link text:

See Also:
equals

Specifying a name - This package.class#member name can be either fully-qualified, such as java.lang.String#toUpperCase() or not, such as String#toUpperCase() or #toUpperCase(). If less than fully-qualified, the Javadoc tool uses the normal Java compiler search order to find it, further described below in Search order for @see. The name can contain whitespace within parentheses, such as between method arguments.

Of course the advantage of providing shorter, "partially-qualified" names is that they are shorter to type and there is less clutter in the source code. The following table shows the different forms of the name, where Class can be a class or interface, Type can be a class, interface, array, or primitive, and method can be a method or constructor.

Typical forms for @see package.class#member
Referencing a member of the current class
@see  #field
@see  #method(Type, Type,...)
@see  #method(Type argname, Type argname,...)
@see  #constructor(Type, Type,...)
@see  #constructor(Type argname, Type argname,...)

Referencing another class in the current or imported packages
@see  Class#field
@see  Class#method(Type, Type,...)
@see  Class#method(Type argname, Type argname,...)
@see  Class#constructor(Type, Type,...)
@see  Class#constructor(Type argname, Type argname,...)
@see  Class.NestedClass
@see  Class

Referencing an element in another package (fully qualified)
@see  package.Class#field
@see  package.Class#method(Type, Type,...)
@see  package.Class#method(Type argname, Type argname,...)
@see  package.Class#constructor(Type, Type,...)
@see  package.Class#constructor(Type argname, Type argname,...)
@see  package.Class.NestedClass
@see  package.Class
@see  package

The following notes apply to the above table:

  • The first set of forms (with no class or package) will cause the Javadoc tool to search only through the current class's hierarchy. It will find a member of the current class or interface, one of its superclasses or superinterfaces, or one of its enclosing classes or interfaces (search steps 1-3). It will not search the rest of the current package or other packages (search steps 4-5).
  • If any method or constructor is entered as a name with no parentheses, such as getValue, and if there is no field with the same name, the Javadoc tool will correctly create a link to it, but will print a warning message reminding you to add the parentheses and arguments. If this method is overloaded, the Javadoc tool will link to the first method its search encounters, which is unspecified.
  • Nested classes must be specified as outer.inner, not simply inner, for all forms.
  • As stated, the hash character (#), rather than a dot (.) separates a member from its class. This enables the Javadoc tool to resolve ambiguities, since the dot also separates classes, nested classes, packages, and subpackages. However, the Javadoc tool is generally lenient and will properly parse a dot if you know there is no ambiguity, though it will print a warning.

Search order for @see - the Javadoc tool will process a @see tag that appears in a source file (.java), package file (package.html) or overview file (overview.html). In the latter two files, you must fully-qualify the name you supply with @see. In a source file, you can specify a name that is fully-qualified or partially-qualified.

When the Javadoc tool encounters a @see tag in a .java file that is not fully qualified, it searches for the specified name in the same order as the Java compiler would (except the Javadoc tool will not detect certain namespace ambiguities, since it assumes the source code is free of these errors). This search order is formally defined in Chapter 6, "Names" of the Java Language Specification, Second Edition. The Javadoc tool searches for that name through all related and imported classes and packages. In particular, it searches in this order:

  1. the current class or interface
  2. any enclosing classes and interfaces, searching closest first
  3. any superclasses and superinterfaces, searching closest first
  4. the current package
  5. any imported packages, classes and interfaces, searching in the order of the import statement

The Javadoc tool continues to search recursively through steps 1-3 for each class it encounters until it finds a match. That is, after it searches through the current class and its enclosing class E, it will search through E's superclasses before E's enclosing classes. In steps 4 and 5, the Javadoc tool does not search classes or interfaces within a package in any specified order (that order depends on the particular compiler). In step 5, the Javadoc tool looks in java.lang, since that is automatically imported by all programs.

The Javadoc tool does not necessarily look in subclasses, nor will it look in other packages even if their documentation is being generated in the same run. For example, if the @see tag is in the java.awt.event.KeyEvent class and refers to a name in the java.awt package, javadoc does not look in that package unless that class imports it.

How a name is displayed - If label is omitted, then package.class.member appears. In general, it is suitably shortened relative to the current class and package. By "shortened", we mean the Javadoc tool displays only the minimum name necessary. For example, if the String.toUpperCase() method contains references to a member of the same class and to a member of a different class, the class name is displayed only in the latter case, as shown in the following table.

Use -noqualifier to globally remove the package names.

Type of Reference Example in String.toUpperCase() Displays As
@see tag refers to member of the same class, same package @see String#toLowerCase()
toLowerCase()
(omits the package and class names)
@see tag refers to member of a different class, same package @see Character#toLowerCase(char)
Character.toLowerCase(char)
(omits the package name, includes the class name)
@see tag refers to member of a different class, different package @see java.io.File#exists()
java.io.File.exists()
(includes the package and class names)

Examples of @see
The comment to the right shows how the name would be displayed if the @see tag is in a class in another package, such as java.applet.Applet. 

                                           See also: 
@see java.lang.String                   //  String                           
@see java.lang.String The String class  //  The String class                 
@see String                             //  String                           
@see String#equals(Object)              //  String.equals(Object)            
@see String#equals                      //  String.equals(java.lang.Object)   
@see java.lang.Object#wait(long)        //  java.lang.Object.wait(long)      
@see Character#MAX_RADIX                //  Character.MAX_RADIX              
@see <a href="spec.html">Java Spec</a>  //  Java Spec            
@see "The Java Programming Language"    //  "The Java Programming Language"
You can extend @see to link to classes not being documented by using the -link option.

For more details, see writing @see tags.

@serial  field-description | include | exclude
Used in the doc comment for a default serializable field.

An optional field-description should explain the meaning of the field and list the acceptable values. If needed, the description can span multiple lines. The standard doclet adds this information to the serialized form page.

If a serializable field was added to a class some time after the class was made serializable, a statement should be added to its main description to identify at which version it was added.

The include and exclude arguments identify whether a class or package should be included or excluded from the serialized form page. They work as follows:

  • A public or protected class that implements Serializable is included unless that class (or its package) is marked @serial exclude.
  • A private or package-private class that implements Serializable is excluded unless that class (or its package) is marked @serial include.

Examples: The javax.swing package is marked @serial exclude (in package.html). The public class java.security.BasicPermission is marked @serial exclude. The package-private class java.util.PropertyPermissionCollection is marked @serial include.

The tag @serial at a class level overrides @serial at a package level.

For more information about how to use these tags, along with an example, see "Documenting Serializable Fields and Data for a Class," Section 1.6 of the Java Object Serialization Specification. Also see the Serialization FAQ, which covers common questions, such as "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 Sun's criteria for including classes in the serialized form specification.

@serialField  field-name  field-type  field-description
Documents an ObjectStreamField component of a Serializable class's serialPersistentFields member. One @serialField tag should be used for each ObjectStreamField component.

@serialData  data-description
The data-description documents the types and order of data in the serialized form. Specifically, this data includes the optional data written by the writeObject method and all data (including base classes) written by the Externalizable.writeExternal method.

The @serialData tag can be used in the doc comment for the writeObject, readObject, writeExternal, and readExternal methods.

@since  since-text
Adds a "Since" heading with the specified since-text to the generated documentation. The text has no special internal structure. This tag is valid in any doc comment: overview, package, class, interface, constructor, method or field. This tag means that this change or feature has existed since the software release specified by the since-text. For example: 
    @since 1.4
For source code in the Java platform, this tag indicates the version of the Java platform API specification (not necessarily when it was added to the reference implementation). Multiple @since tags are allowed and are treated like multiple @author tags. You could use multiple tags if the prgram element is used by more than one API.

@throws  class-name  description
The @throws and @exception tags are synonyms. Adds a "Throws" subheading to the generated documentation, with the class-name and description text. The class-name is the name of the exception that may be thrown by the method. This tag is valid only in the doc comment for a method or constructor. If this class is not fully-specified, the Javadoc tool uses the search order to look up this class. Multiple @throws tags can be used in a given doc comment for the same or different exceptions.

To ensure that all checked exceptions are documented, if a @throws tag does not exist for an exception in the throws clause, the Javadoc tool automatically adds that exception to the HTML output (with no description) as if it were documented with @throws tag.

The @throws documentation is copied from an overridden method to a subclass only when the exception is explicitly declared in the overridden method. The same is true for copying from an interface method to an implementing method. You can use {@inheritDoc} to force @throws to inherit documentation.

For more details, see writing @throws tags.

{@value}
When used in the doc comment of a static field, displays the value of the constant. These are the values displayed on the Constant Field Values page. This tag is valid only in doc comments for fields.

@version  version-text
Adds a "Version" subheading with the specified version-text to the generated docs when the -version option is used. This tag is intended to hold the current version number of the software that this code is part of (as opposed to @since, which holds the version number where this code was introduced). The version-text has no special internal structure. To see where the version tag can be used, see Where Tags Can Be Used.

A doc comment may contain multiple @version tags. If it makes sense, you can specify one version number per @version tag or multiple version numbers per tag. In the former case, the Javadoc tool inserts a comma (,) and space between names. In the latter case, the entire text is simply copied to the generated document without being parsed. Therefore, you can use multiple names per line if you want a localized name separator other than comma.

For more details, see writing @version tags.


Where Tags Can Be Used

The following sections describe where the tags can be used. Note that these tags can be used in all doc comments: @see, @since, @deprecated, {@link}, {@linkplain}, and {@docroot}.


Overview Documentation Tags

Overview tags are tags that can appear in the documentation comment for the overview page (which resides in the source file typically named overview.html). Like in any other documentation comments, these tags must appear after the main description.

NOTE - The {@link} tag has a bug in overview documents in version 1.2 -- the text appears properly but has no link. The {@docRoot} tag does not currently work in overview documents.

Overview Tags
@see
@since
@author
@version
{@link}
{@linkplain}
{@docRoot}

Package Documentation Tags

Package tags are tags that can appear in the documentation comment for a package (which resides in the source file named package.html). The @serial tag can only be used here with the include or exclude argument.

Package Tags
@see
@since
@serial
@author
@version
{@link}
{@linkplain}
{@docRoot}

Class and Interface Documentation Tags

The following are tags that can appear in the documentation comment for a class or interface. The @serial tag can only be used here with the include or exclude argument.

Class/Interface Tags
@see
@since
@deprecated
@serial
@author
@version
{@link}
{@linkplain}
{@docRoot}

An example of a class comment:

/**
 * A class representing a window on the screen.
 * For example:
 * <pre>
 *    Window win = new Window(parent);
 *    win.show();
 * </pre>
 *
 * @author  Sami Shaio
 * @version %I%, %G%
 * @see     java.awt.BaseWindow
 * @see     java.awt.Button
 */
class Window extends BaseWindow {
   ...
}

Field Documentation Tags

The following are the tags that can appear in the documentation comment for a field.

Field Tags
@see
@since
@deprecated
@serial
@serialField
{@link}
{@linkplain}
{@docRoot}
{@value}

An example of a field comment:

    /**
     * The X-coordinate of the component.
     *
     * @see #getLocation()
     */
    int x = 1263732;

Constructor and Method Documentation Tags

The following are the tags that can appear in the documentation comment for a constructor or method, except for @return, which cannot appear in a constructor, and {@inheritDoc}, which has certain restrictions. The @serialData tag can only be used in the doc comment for certain serialization methods.

Method/Constructor Tags
@see
@since
@deprecated
@param
@return
@throws and @exception
@serialData
{@link}
{@linkplain}
{@inheritDoc}
{@docRoot}

An example of a method doc comment:

    /**
     * Returns the character at the specified index. An index 
     * ranges from <code>0</code> to <code>length() - 1</code>.
     *
     * @param     index  the index of the desired character.
     * @return    the desired character.
     * @exception StringIndexOutOfRangeException 
     *              if the index is not in the range <code>0</code> 
     *              to <code>length()-1</code>.
     * @see       java.lang.Character#charValue()
     */
    public char charAt(int index) {
       ...
    }

OPTIONS
The javadoc tool uses doclets to determine its output. The Javadoc tool uses the default standard doclet unless a custom doclet is specified with the -doclet option. The Javadoc tool provides a set of command-line options that can be used with any doclet -- these options are described below under the sub-heading Javadoc Options. The standard doclet provides an additional set of command-line options that are described below under the sub-heading Options Provided by the Standard Doclet. All option names are case-insensitive, though their arguments can be case-sensitive.

The options are:

-1.1
-author
-bootclasspath
-bottom
-breakiterator
-charset
-classpath
-d
-docencoding
-docfilessubdirs
-doclet
-docletpath
-doctitle
-encoding
-exclude
-excludedocfilessubdir
-extdirs
-footer
-group
 -header
-help
-helpfile
-J
-link
-linkoffline
-linksource
-locale
-nocomment
-nodeprecated
-nodeprecatedlist
-nohelp
-noindex
-nonavbar
-noqualifier
-nosince
-notree
-overview
-package
 -private
-protected
-public
-quiet
-serialwarn
-source
-sourcepath
-splitindex
-stylesheetfile
-subpackages
-tag
-taglet
-tagletpath
-title
-use
-verbose
-version
-windowtitle
Options shown in italic are the Javadoc core options, which are provided by the front end of the Javadoc tool and are available to all doclets. The standard doclet itself provides the non-italic options.

Javadoc Options

-overview  path/filename
Specifies that javadoc should retrieve the text for the overview documentation from the "source" file specified by path/filename and place it on the Overview page (overview-summary.html). The path/filename is relative to the -sourcepath.

While you can use any name you want for filename and place it anywhere you want for path, a typical thing to do is to name it overview.html and place it in the source tree at the directory that contains the topmost package directories. In this location, no path is needed when documenting packages, since -sourcepath will point to this file. For example, if the source tree for the java.lang package is /src/classes/java/lang/, then you could place the overview file at /src/classes/overview.html. See Real World Example.

For information about the file specified by path/filename, see overview comment file.

Note that the overview page is created only if you pass into javadoc two or more package names. For further explanation, see HTML Frames.)

The title on the overview page is set by -doctitle.

-public
Shows only public classes and members.

-protected
Shows only protected and public classes and members. This is the default.

-package
Shows only package, protected, and public classes and members.

-private
Shows all classes and members.

-help
Displays the online help, which lists these javadoc and doclet command line options.

-doclet  class
Specifies the class file that starts the doclet used in generating the documentation. Use the fully-qualified name. This doclet defines the content and formats the output. If the -doclet option is not used, javadoc uses the standard doclet for generating the default HTML format. This class must contain the start(Root) method. The path to this starting class is defined by the -docletpath option.

For example, to call the MIF doclet, use: 

    -doclet com.sun.tools.doclets.mif.MIFDoclet

-docletpath  classpathlist
Specifies the path to the doclet starting class file (specified with the -doclet option) and any jar files it depends on. If the starting class file is in a jar file, then this specifies the path to that jar file, as shown in the example below. You can specify an absolute path or a path relative to the current directory. If classpathlist contains multiple paths or jar files, they should be separated with a colon (:) on Solaris and a semi-colon (;) on Windows. This option is not necessary if the doclet starting class is already in the search path.

Example of path to jar file that contains the starting doclet class file. Notice the jar filename is included. 

   -docletpath /home/user/mifdoclet/lib/mifdoclet.jar
Example of path to starting doclet class file. Notice the class filename is omitted. 
   -docletpath /home/user/mifdoclet/classes/com/sun/tools/doclets/mif/
-1.1
This feature has been removed from Javadoc 1.4. There is no replacement for it. This option created documentation with the appearance and functionality of documentation generated by Javadoc 1.1 (it never supported nested classes). If you need this option, use Javadoc 1.2 or 1.3 instead.

-source  1.4
Necessary to enable javadoc to handle assertions present in J2SE v 1.4 source code. This option documents code that compiles using "javac -source 1.4",

-sourcepath  sourcepathlist
Specifies the search paths for finding source files (.java) when passing package names or -subpackages into the javadoc command. The sourcepathlist can contain multiple paths by separating them with a colon (:). The Javadoc tool will search in all subdirectories of the specified paths. Note that this option is not only used to locate the source files being documented, but also to find source files that are not being documented but whose comments are inherited by the source files being documented.

Note that you can use the -sourcepath option only when passing package names into the javadoc command -- it will not locate .java files passed into the javadoc command. (To locate .java files, cd to that directory or include the path ahead of each file, as shown at Documenting One or More Classes.) If -sourcepath is omitted, javadoc uses the class path to find the source files (see -classpath). Therefore, the default -sourcepath is the value of class path. If -classpath is omitted and you are passing package names into javadoc, it looks in the current directory (and subdirectories) for the source files.

Set sourcepathlist to the root directory of the source tree for the package you are documenting. For example, suppose you want to document a package called com.mypackage whose source files are located at: 

  /home/user/src/com/mypackage/*.java
In this case you would specify the sourcepath to /home/user/src, the directory that contains com/mypackage, and then supply the package name com.mypackage: 
  % javadoc -sourcepath /home/user/src/ com.mypackage
This is easy to remember by noticing that if you concatenate the value of sourcepath and the package name together and change the dot to a slash "/", you end up with the full path to the package: /home/user/src/com/mypackage.

To point to two source paths: 

  % javadoc -sourcepath /home/user1/src:/home/user2/src com.mypackage

-classpath  classpathlist
Specifies the paths where javadoc will look for referenced classes (.class files) -- these are the documented classes plus any classes referenced by those classes. The classpathlist can contain multiple paths by separating them with a colon (:). The Javadoc tool will search in all subdirectories of the specified paths. Follow the instructions in class path documentation for specifying classpathlist.

If -sourcepath is omitted, the Javadoc tool uses -classpath to find the source files as well as class files (for backward compatibility). Therefore, if you want to search for source and class files in separate paths, use both -sourcepath and -classpath.

For example, if you want to document com.mypackage, whose source files reside in the directory /home/user/src/com/mypackage, and if this package relies on a library in /home/user/lib, you would specify: 

  % javadoc -classpath /home/user/lib -sourcepath /home/user/src com.mypackage
As with other tools, if you do not specify -classpath, the Javadoc tool uses the CLASSPATH environment variable, if it is set. If both are not set, the Javadoc tool searches for classes from the current directory.

For an in-depth description of how the Javadoc tool uses -classpath to find user classes as it relates to extension classes and bootstrap classes, see How Classes Are Found.

-bootclasspath  classpathlist
Specifies the paths where the boot classes reside. These are nominally the Java platform classes. The bootclasspath is part of the search path the Javadoc tool will use to look up source and class files. See How Classes Are Found. for more details. Separate directories in classpathlist with colons (:).

-extdirs  dirlist
Specifies the directories where extension classes reside. These are any classes that use the Java Extension mechanism. The extdirs is part of the search path the Javadoc tool will use to look up source and class files. See -classpath (above) for more details. Separate directories in dirlist with colons (:).

-verbose
Provides more detailed messages while javadoc is running. Without the verbose option, messages appear for loading the source files, generating the documentation (one message per source file), and sorting. The verbose option causes the printing of additional messages specifying the number of milliseconds to parse each java source file.

-quiet
Shuts off non-error and non-warning messages, leaving only the warnings and errors appear, making them easier to view. Also suppresses the version string.

-locale  language_country_variant
Important - The -locale option must be placed ahead (to the left) of any options provided by the standard doclet or any other doclet. Otherwise, the navigation bars will appear in English. This is the only command-line option that is order-dependent.
Specifies the locale that javadoc uses when generating documentation. The argument is the name of the locale, as described in java.util.Locale documentation, such as en_US (English, United States) or en_US_WIN (Windows variant).

Specifying a locale causes javadoc to choose the resource files of that locale for messages (strings in the navigation bar, headings for lists and tables, help file contents, comments in stylesheet.css, and so forth). It also specifies the sorting order for lists sorted alphabetically, and the sentence separator to determine the end of the first sentence. It does not determine the locale of the doc comment text specified in the source files of the documented classes.

-encoding  name
Specifies the encoding name of the source files, such as EUCJIS/SJIS. If this option is not specified, the platform default converter is used.

Also see -docencoding and -charset.

-Jflag
Passes flag directly to the runtime system java that runs javadoc. Notice there must be no space between the J and the flag. For example, if you need to ensure that the system sets aside 32 megabytes of memory in which to process the generated documentation, then you would call the -Xmx option of java as follows (-Xms is optional, as it only sets the size of initial memory, which is useful if you know the minimum amount of memory required): 
   % javadoc -J-Xmx32m -J-Xms32m com.mypackage
To tell what version of javadoc you are using, call the "-version" option of java: 

   % javadoc -J-version
   java version "1.2"
   Classic VM (build JDK-1.2-V, green threads, sunwjit)
(The version number of the standard doclet appears in its output stream.)

Options Provided by the Standard Doclet

-d  directory
Specifies the destination directory where javadoc saves the generated HTML files. (The "d" means "destination.") Omitting this option causes the files to be saved to the current directory. The value directory can be absolute, or relative to the current working directory. As of 1.4, the destination directory is automatically created when javadoc is run.

For example, the following generates the documentation for the package com.mypackage and saves the results in the /home/user/doc/ directory: 

  % javadoc -d /home/user/doc com.mypackage

-use
Includes one "Use" page for each documented class and package. The page describes what packages, classes, methods, constructors and fields use any API of the given class or package. Given class C, things that use class C would include subclasses of C, fields declared as C, methods that return C, and methods and constructors with parameters of type C.

For example, let's look at what might appear on the "Use" page for String. The getName() method in the java.awt.Font class returns type String. Therefore, getName() uses String, and you will find that method on the "Use" page for String.

Note that this documents only uses of the API, not the implementation. If a method uses String in its implementation but does not take a string as an argument or return a string, that is not considered a "use" of String.

You can access the generated "Use" page by first going to the class or package, then clicking on the "Use" link in the navigation bar.

-version
Includes the @version text in the generated docs. This text is omitted by default. To tell what version of the Javadoc tool you are using, use the -J-version option.

-author
Includes the @author text in the generated docs.

-splitindex
Splits the index file into multiple files, alphabetically, one file per letter, plus a file for any index entries that start with non-alphabetical characters.

-windowtitle  title
Specifies the title to be placed in the HTML <title> tag. This appears in the window title and in any browser bookmarks (favorite places) that someone creates for this page. This title should not contain any HTML tags, as the browser will not properly interpret them. Any internal quotation marks within title may have to be escaped. If -windowtitle is omitted, the Javadoc tool uses the value of -doctitle for this option. 

  % javadoc -windowtitle "Java 2 Platform" com.mypackage
-doctitle  title
Specifies the title to be placed near the top of the overview summary file. The title will be placed as a centered, level-one heading directly beneath the upper navigation bar. The title may contain html tags and white space, though if it does, it must be enclosed in quotes. Any internal quotation marks within title may have to be escaped. 

  % javadoc -doctitle "Java<sup><font size=\"-2\">TM</font></sup>" com.mypackage
-title  title
This option no longer exists. It existed only in Beta versions of Javadoc 1.2. It has been renamed to -doctitle. This option is being renamed to make it clear that it defines the document title rather than the window title.

-header  header
Specifies the header text to be placed at the top of each output file. The header will be placed to the right of the upper navigation bar. header may contain HTML tags and white space, though if it does, it must be enclosed in quotes. Any internal quotation marks within header may have to be escaped. 

  % javadoc -header "<b>Java 2 Platform </b><br>v1.4" com.mypackage

-footer  footer
Specifies the footer text to be placed at the bottom of each output file. The footer will be placed to the right of the lower navigation bar. footer may contain html tags and white space, though if it does, it must be enclosed in quotes. Any internal quotation marks within footer may have to be escaped.

-bottom  text
Specifies the text to be placed at the bottom of each output file. The text will be placed at the bottom of the page, below the lower navigation bar. The text may contain HTML tags and white space, though if it does, it must be enclosed in quotes. Any internal quotation marks within text may have to be escaped.

-link  extdocURL
Creates links to existing javadoc-generated documentation of external referenced classes. It takes one argument:

  • extdocURL is the absolute or relative URL of the directory containing the external javadoc-generated documentation you want to link to. Examples are shown below. The package-list file must be found in this directory (otherwise, use -linkoffline). The Javadoc tool reads the package names from the package-list file and then links to those packages at that URL. When the Javadoc tool is run, the extdocURL value is copied literally into the <A HREF> links that are created. Therefore, extdocURL must be the URL to the directory, not to a file.

    You can use an absolute link for extdocURL to enable your docs to link to a document on any website, or can use a relative link to link only to a relative location. If relative, the value you pass in should be the relative path from the destination directory (specified with -d) to the directory containing the packages being linked to.

    When specifying an absolute link you normally use an http: link. However, if you want to link to a file system that has no web server, you can use a file: link -- however, do this only if everyone wanting to access the generated documentation shares the same file system.

    In all cases, and on all operating systems, you should use a forward slash as the separator, whether the URL is absolute or relative, and "http:" or "file:" based (as specified in the URL Memo).

    Absolute http: based link:
    -link http://<host>/<directory>/<directory>/.../<name>
    Absolute file: based link:
    -link file://<host>/<directory>/<directory>/.../<name>
    Relative link:
    -link <directory>/<directory>/.../<name>

You can specify multiple -link options in a given javadoc run to link to multiple documents.

Choosing between -linkoffline and -link:
Use -link:

  • when using a relative path to the external API document, or
  • when using an absolute URL to the external API document, if your shell allows a program to open a connection to that URL for reading.
Use -linkoffline:
  • when using an absolute URL to the external API document, if your shell does not allow a program to open a connection to that URL for reading. This can occur if you are behind a firewall and the document you want to link to is on the other side.

Example using absolute links to the external docs - Let's say you want to link to the java.lang, java.io and other Java 2 Platform packages at http://java.sun.com/j2se/1.4.2/docs/api, The following command generates documentation for the package com.mypackage with links to the Java 2 Platform packages. The generated documentation will contain links to the Object class, for example, in the class trees. (Other options, such as -sourcepath and -d, are not shown.) 

  % javadoc -link http://java.sun.com/j2se/1.4.2/docs/api com.mypackage
Example using relative links to the external docs - Let's say you have two packages whose docs are generated in different runs of the Javadoc tool, and those docs are separated by a relative path. In this example, the packages are com.apipackage, an API, and com.spipackage, an SPI (Service Provide Interface). You want the documentation to reside in docs/api/com/apipackage and docs/spi/com/spipackage. Assuming the API package documentation is already generated, and that docs is the current directory, you would document the SPI package with links to the API documentation by running: 
  % javadoc -d ./spi -link ../api com.spipackage

Notice the -link argument is relative to the destination directory (docs/spi).

Details - The -link option enables you to link to classes referenced to by your code but not documented in the current javadoc run. For these links to go to valid pages, you must know where those HTML pages are located, and specify that location with extdocURL. This allows, for instance, third party documentation to link to java.* documentation on http://java.sun.com.

Omit the -link option for javadoc to create links only to API within the documentation it is generating in the current run. (Without the -link option, the Javadoc tool does not create links to documentation for external references, because it does not know if or where that documentation exists.)

This option can create links in several places in the generated documentation.

Another use is for cross-links between sets of packages: Execute javadoc on one set of packages, then run javadoc again on another set of packages, creating links both ways between both sets.

How a Cl