Javadoc is a documentation generator created by Sun Microsystems for the Java language (now owned by Oracle Corporation) for generating API documentation in HTML format from Java source code. The HTML format is used for adding the convenience of being able to hyperlink related documents together.[1]
The "doc comments" format[2] used by Javadoc is the de facto industry standard for documenting Java classes. Some IDEs,[3] like IntelliJ IDEA, NetBeans and Eclipse, automatically generate Javadoc templates. Many file editors assist the user in producing Javadoc source and use the Javadoc info as internal references for the programmer.
Javadoc also provides an API for creating doclets and taglets, which allows users to analyze the structure of a Java application. This is how JDiff can generate reports of what changed between two versions of an API.
Javadoc does not affect performance in Java as all comments are removed at compilation time. Writing comments and Javadoc is for better understanding the code and thus better maintaining it.
Javadoc was an early Java language documentation generator.[4] Prior to the use of documentation generators it was customary to use technical writers who would typically write only standalone documentation for the software,[5] but it was much harder to keep this documentation in sync with the software itself.
Javadoc has been used by Java since the first release, and is usually updated upon every new release of the Java Development Kit.
The @field syntax of Javadoc has been emulated by documentation systems for other languages, including the cross-language Doxygen, the JSDoc system for JavaScript, EDoc for Erlang, and Apple's HeaderDoc.
A Javadoc comment is set off from code by standard multi-line comment tags /* and */. The opening tag (called begin-comment delimiter), has an extra asterisk, as in /**.
@param)@return)@throws)@see (a "see also" tag)Most Javadoc comments are imbedded inside /** ... */ tags. The Javadoc comment block is positioned immediately above the itemswithout any separating newline, and below any import statements.The class declaration usuallycontains:
/** * @author Firstname Lastname
* @version 1.6 (current version number of program) * @since 1.2 (the version of the package this class was first added to) */public class TestDocumentation comments for methods usually contain a short, concise, one line description toexplain what the item does, followed by a longer description, and lastly a tag section that lists accepted input arguments and return values of the method. TheJavadoc is treated as HTML, so a "<p>" paragraph break tag can be used to denote multiple paragraphs.
* Longer description. If there were any, it would be (2) * here. * * And even more explanations to follow in consecutive * paragraphs separated by HTML paragraph breaks. * * @param variable Description text text text. (3) * @return Description text text text. */public int methodName (...)
Variables are documented similarly to methods, but often lack the tags at the end of the comment.
It is not recommended[6] to define multiple variables in a single documentation comment, as Javadoc reads each variable and places them separately to the generated HTML page with the same documentation comment that is copied for all fields.
Instead, it is recommended to write and document each variable separately:
/** * The vertical distance of point. */public int y;
Some of the available Javadoc tags[7] are listed in the table below:
| Tag & Parameter | Usage | Applies to | Since |
|---|---|---|---|
| @author John Smith | Describes an author. | Class, Interface, Enum | |
| Represents the relative path to the generated document's root directory from any generated page. | Class, Interface, Enum, Field, Method | ||
| @version version | Provides software version information. | Module, Package, Class, Interface, Enum | |
| @since since-text | Describes when this functionality has first existed. | Class, Interface, Enum, Field, Method | |
| @see reference | Provides a link to other element of documentation. | Class, Interface, Enum, Field, Method | |
| @param name description | Describes a method parameter. | Method | |
| @return description | Describes the return value. | Method | |
| @exception classname description @throws classname description | Describes an exception that may be thrown from this method. | Method | |
| @deprecated description | Describes an outdated method. | Class, Interface, Enum, Field, Method | |
| Copies the description from the overridden method. | Overriding Method | 1.4.0 | |
| Link to other symbol. | Class, Interface, Enum, Field, Method | ||
| Identical to, except the link's label is displayed in plain text than code font. | Class, Interface, Enum, Field, Method | ||
| Return the value of a static field. | Static Field | 1.4.0 | |
Formats literal text in the code font. It is equivalent to <code>{@literal}</code>. || Class, Interface, Enum, Field, Method||1.5.0|-||| Denotes literal text. The enclosed text is interpreted as not containing HTML markup or nested javadoc tags. || Class, Interface, Enum, Field, Method||1.5.0|-||Used in the doc comment for a default serializable field.|Field||-||Documents the data written by the writeObject or writeExternal methods.|Field, Method||-||Documents an ObjectStreamField component.|Field||}ExamplesAn example of Javadoc to document a method follows. Notice that spacing and number of characters in this example are as conventions state. Use to move a piece. * * @param fromFile file from which a piece is being moved * @param fromRank rank from which a piece is being moved * @param toFile file to which a piece is being moved * @param toRank rank to which a piece is being moved * @return true if the move is valid, otherwise false * @since 1.0 */boolean isValidMove(int fromFile, int fromRank, int toFile, int toRank) /** * Moves a chess piece. * * @see java.math.RoundingMode */void doMove(int fromFile, int fromRank, int toFile, int toRank) DocletsDoclet programs work with the Javadoc tool to generate documentation from code written in Java.[8] Doclets are written in the Java programming language and use the to:
The https://docs.oracle.com/javase/9/javadoc/javadoc-command.htm#JSJAV-GUID-04BFA924-7C45-4E9C-91D1-0B77D97E65AB included with Javadoc generates API documentation as frame-based HTML files. Many non-standard doclets are available on the web, often for free. These can be used to:
See also
External links
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