javadoc - The Java API Documentation Generator

Generates HTML pages of API documentation from Java source files.

SYNOPSIS

javadoc [ options ] [ package | source.java ]*

DESCRIPTION

javadoc parses the declarations and documentation comments in a set of Java source files and produces a set of HTML pages describing, by default, the public and protected classes, interfaces, constructors, methods, and fields. As an argument to javadoc you pass in either a series of Java package names or source files.

javadoc generates one .html file for each .java file and each packages it encounters. In addition, it produces a class hierarchy (tree.html) and an index of those members (AllNames.html).

When javadoc parses the class and member delarations, it picks up their signatures for inclusion. In addition, you can add further documentation by including doc comments in the source code.

Commenting the Source Code

You can include documentation comments in the source code. A doc comment consists of the characters between the /** that begins the comment and the */ that ends it. The text is divided into one or more lines. When javadoc parses a doc comment, leading * characters on each line are discarded; for lines other than the first, blanks and tabs preceding the initial * characters are also discarded. These comments may include HTML tags. Here is a doc comment:

/**
 * This is a <b>doc</b> comment.
 */

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 tag (as defined below). javadoc copies this first sentence to the member summary at the top of the .html file.

Documentation comments are only recognized when placed immediately before class, interface, constructor, method, or field declarations.

When you embed HTML tags within a doc commen, you should not use heading tags such as <h1> and <h2>, because javadoc creates an entire structured document and these structural tags interfere with the formatting of the generated document.

For the specification on documentation comments, see Chapter 18, Documentation Comments, in the Java Language Specification, by James Gosling, Bill Joy, and Guy Steele.

Tagged Paragraphs

javadoc parses special tags that are recognized 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 (@).

Tags must start at the beginning of a line. Keep tags with the same name together within a doc comment. For example, put all @author tags together so that javadoc can tell where the list ends.

The tags fall into three categories: Class/interface tags, field tags, and constructor/method tags; each is itemized in the following sections.

Class and Interface Documentation Tags

@author name-text
Creates an "Author" entry. The text has no special internal structure. A doc comment may contain multiple @author tags.

@version version-text
Adds a "Version" entry. The text has no special internal structure. A doc comment may contain at most one @version tag. Version normally refers to the version of the software (such as the JDK) that contains this feature.

@see classname
Adds a hyperlinked "See Also" entry to the class. Some examples are:
    @see java.lang.String
    @see String
    @see String#equals
    @see java.lang.Object#wait(int)
    @see Character#MAX_RADIX
    @see <a href="spec.html">Java Spec</a>
The character # separates the name of a class from the name of one of its fields, methods, or constructors. One of several overloaded methods or constructors may be selected by including a parenthesized list of argument types after the method or constructor name. Whitespace in @see's classname is significant. If there is more than one argument, there must be a single blank character between the arguments. For example:
    @see java.io.File#File(java.io.File, java.lang.String)

A doc comment may contain more than one @see tag.

@since since-text
Adds a "Since" entry. The text has no special internal structure. This tag means that this change or feature has existed since the release number of the software specified by the since-text (such as the JDK).

@deprecated deprecated-text
Adds a deprecated comment indicating that this API should no longer be used (even though it may continue to work). The convention is to describe the API that serves as a replacement. For example:
    @deprecated  Replaced by setBounds(int, int, int, int).
If the member is obsolete and there is no replacement, the argument to @deprecated should be "No replacement".

For more about this tag, see Deprecation of APIs.

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

A field comment can contain only the @see, @since and @deprecated tags (as described above).

An example of a field comment:

    /**
     * The X-coordinate of the window.
     *
     * @see window#1
     */
    int x = 1263732;

Constructor and Method Documentation Tags

Can contain @see tags, as well as:
@param parameter-name description
Adds a parameter to the "Parameters" section. The description may be continued on the next line.

@return description
Adds a "Returns" section, which contains the description of the return value.

@exception fully-qualified-class-name description
Adds a "Throws" section, which contains the name of the exception that may be thrown by the method. The exception is linked to its class documentation.

@see classname
Adds a hyperlinked "See Also" entry to the method. This tag is described above.

@since since-text
See the description above.

@deprecated deprecated-text
See the description above.

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

-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.

-Jflag
Pass flag directly to the runtime system. For example, if you need to ensure that the system sets aside 32 megabytes of memory to hold the generated documentation, then you would use this flag as follows:
javadoc -J-mx32m -J-ms32m <classes> ...

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

-docencoding  name
Specify output HTML file encoding name.

-version
Include @version tags, which are omitted by default.

-author
Include @author tags, which are omitted by default.

-noindex
Omit the package index, which is produced by default.

-notree
Omit the class/interface hierarchy, which is produced by default.

-d  directory
Specifies the destination directory where javadoc stores the generated HTML files. (The "d" means "destination.") The directory can be absolute or relative to the current working directory. For example, the following generates the documentation for the java.lang package (using CLASSPATH to find it) and stores the results in the directory specified by the -d option:
javadoc -d /home/opus/public_html/doc java.lang
-verbose
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.

-sourcepath  path
Specifies the search path for source files. Does not affect the loading of class files. The sourcepath you specify depends on whether you specify packages or classes as arguments to the javadoc command.

When generating documentation for packages, specify sourcepath as the directory in the source tree that contains the top-most parent package of the packages you are documenting. The default for sourcepath is the current classpath directory. For example, suppose you want to document a package called java.lang whose source files are located at:

/myapp/src/share/java/lang/*.java
Because java is the top-most parent package, you would specify the sourcepath to be the directory that contains java:
-sourcepath /myapp/src/share
When generating documentation for discrete classes, specify sourcepath as the directory in the source tree that contains the classes you are documenting. Note that this is different from the sourcepath you used when documenting packages. For example, suppose you want to document a class named java.lang.String whose source file is located at:
/myapp/src/share/java/lang/String.java
Specify the sourcepath to be the directory that contains the class String.java:
-sourcepath /myapp/src/share/java/lang
You can omit the sourcepath option if you first switch to the directory you would have specified.

-classpath  path
NOTE: In general, do not use -classpath, because it is normally not needed; use -sourcepath instead to specify .java files.

Specifies the directories from which javadoc is to load the .class files used to execute the javadoc tool. If -sourcepath is not specified, this also specifies the path javadoc uses to look up the .java files to document. It overrides the default or the CLASSPATH environment variable, if it is set. The path can contain multiple paths by separating them with a colon. Se the path the same way you do for the CLASSPATH environment variable. For example, the following sets two paths: current directory (.) and /home/opus/myclasses:

javadoc -classpath .:/home/opus/myclasses myPackage.MyClass

The -classpath option is not necessary if you call javadoc wrapper script directly. Normally, if you specify classpath it must precede sourcepath. However, the order of these two options does not matter if you are using the wrapper script.

The value of classpath defaults to the current directory plus the classes location, as described in the CLASSPATH environment variable.

-nodeprecated
Exclude paragraphs with the @deprecated tag.

NOTE: The -doctype option is no longer available. Only HTML documentation can be produced.

EXAMPLES

Each package name has a corresponding directory name. In the following examples, the source files are located at /home/ws/src/java/awt/*java. The destination directory is /home/ws/html.

Documenting One or More Packages

To document a package, the source files (*.java) for that package must be located in a directory having the same name as the package. If a package name is made up of several identifiers (separated by dots), each identifier represents a different directory. Thus, all java.awt classes must reside in a directory named java/awt/.

First, change to the parent directory of the top-most package (or supply the sourcepath option with that directory). Then run javadoc, supplying one or more fully-specified package names. For example, if you want to document the source files in the java.awt package located at /home/ws/src/java/awt/*.java and its subpackage java.awt.event:

  % cd /home/ws/src/
  % javadoc -d /home/ws/html java.awt java.awt.event
This generates HTML-formatted documentation for the public classes in packages java.awt and java.awt.event and puts it in the specified destination directory (/home/ws/html).

Documenting One or More Classes

Change to the directory holding the class (or supply the sourcepath option with that directory). Then run javadoc, supplying one or more class names. For example, to document classes at the same level as /home/ws/src/java/awt/Button.java:
  % cd /home/ws/src/java/awt
  % javadoc -d /home/ws/html Button.java Canvas.java
This generates HTML-formatted documentation for the two classes and puts it in the specified destination directory (/home/ws/html).

ENVIRONMENT

CLASSPATH
Provides the system a path to the user-defined classes. Separate directories with a colon, for example,
.:/home/avh/classes:/usr/local/java/classes

SEE ALSO

javac, java, jdb, javah, javap, CLASSPATH, Javadoc Home Page