Java中的注释

在程序中，注释通过放置所涉及的代码细节来使程序变得更易于阅读，正确使用注释可以使维护更容易并容易发现错误。编译代码时，编译器会忽略注释。
Java中的注释分为三种：

1. 单行注释。
2. 多行注释。
3. 文档评论。

单行注释

初级程序员主要使用单行注释来描述代码功能。它是最简单的打字评论。
句法：

//Comments here( Text in this line only is considered as comment )

例子：

Java

//Java program to show single line comments
class Scomment
{
    public static void main(String args[])
    {
         // Single line comment here
         System.out.println("Single line comment above");
    }
}

多行注释

要在代码或复杂的代码片段中描述完整的方法，单行注释可能会很乏味，因为我们必须在每一行都给出“//”。因此，可以使用多行注释来克服这种情况。
句法：

/*Comment starts
continues
continues
.
.
.
Comment ends*/

例子：

Java

//Java program to show multi line comments
class Scomment
{
    public static void main(String args[])
    {
        System.out.println("Multi line comments below");
        /*Comment line 1
          Comment line 2
          Comment line 3*/
    }
}

我们也可以使用上面的语法来完成单行注释，如下所示：

/*Comment line 1*/

文档评论

这种类型的注释通常在为项目/软件包编写代码时使用，因为它有助于生成一个文档页面以供参考，该页面可用于获取有关当前方法、其参数等的信息。
例如 http://docs.oracle.com/javase/7/docs/api/ Java/util/Scanner.html 是一个自动生成的文档页面，它是通过使用文档注释和用于处理注释的 javadoc 工具生成的。
句法：

/**Comment start
*
*tags are used in order to specify a parameter
*or method or heading
*HTML tags can also be used 
*such as 

*
*comment ends*/

可用的标签：

Tag	Description	Syntax
@author	Adds the author of a class.	@author name-text
{@code}	Displays text in code font without interpreting the text as HTML markup or nested javadoc tags.	{@code text}
{@docRoot}	Represents the relative path to the generated document’s root directory from any generated page.	{@docRoot}
@deprecated	Adds a comment indicating that this API should no longer be used.	@deprecated deprecatedtext
@exception	Adds a Throws subheading to the generated documentation, with the classname and description text.	@exception class-name description
{@inheritDoc}	Inherits a comment from the nearest inheritable class or implementable interface.	Inherits a comment from the immediate surperclass.
{@link}	Inserts an in-line link with the visible text label that points to the documentation for the specified package, class, or member name of a referenced class.	{@link package.class#member label}
{@linkplain}	Identical to {@link}, except the link’s label is displayed in plain text than code font.	{@linkplain package.class#member label}
@param	Adds a parameter with the specified parameter-name followed by the specified description to the “Parameters” section.	@param parameter-name description
@return	Adds a “Returns” section with the description text.	@return description
@see	Adds a “See Also” heading with a link or text entry that points to reference.	@see reference
@serial	Used in the doc comment for a default serializable field.	@serial field-description | include | exclude
@serialData	Documents the data written by the writeObject( ) or writeExternal( ) methods.	@serialData data-description
@serialField	Documents an ObjectStreamField component.	@serialField field-name field-type field-description
@since	Adds a “Since” heading with the specified since-text to the generated documentation.	@since release
@throws	The @throws and @exception tags are synonyms.	@throws class-name description
{@value}	When {@value} is used in the doc comment of a static field, it displays the value of that constant.	{@value package.class#field}
@version	Adds a “Version” subheading with the specified version-text to the generated docs when the -version option is used.	@version version-text

Java

//Java program to illustrate frequently used
// Comment tags
 
/**
* 
Find average of three numbers!
* The FindAvg program implements an application that
* simply calculates average of three integers and Prints
* the output on the screen.
*
* @author  Pratik Agarwal
* @version 1.0
* @since   2017-02-18
*/
public class FindAvg
{
    /**
    * This method is used to find average of three integers.
    * @param numA This is the first parameter to findAvg method
    * @param numB  This is the second parameter to findAvg method
    * @param numC  This is the second parameter to findAvg method
    * @return int This returns average of numA, numB and numC.
    */
    public int findAvg(int numA, int numB, int numC)
    {
        return (numA + numB + numC)/3;
    }
 
    /**
    * This is the main method which makes use of findAvg method.
    * @param args Unused.
    * @return Nothing.
    */
 
    public static void main(String args[])
    {
        FindAvg obj = new FindAvg();
        int avg = obj.findAvg(10, 20, 30);
 
        System.out.println("Average of 10, 20 and 30 is :" + avg);
    }
}

输出：

Average of 10, 20 and 30 is :20

对于上述代码文档，可以使用工具 'javadoc' 生成：
可以通过在终端中运行以下命令来使用 Javadoc。

javadoc FindAvg.java