Java查看某个类的帮助文档

1、找到java的安装路径，我拿我自己的安装路径举例：
2、我想查找String类的使用方法，首先你要知道String所属包名，String是java.lang.String，一下是查看帮助文档的路径：

C:\Program Files\Java\jdk1.7.0_67\src.zip\java\lang\String.java	

找到注释：

/**
 * The String class represents character strings. All
 * string literals in Java programs, such as "abc", are
 * implemented as instances of this class.
 * 

 * Strings are constant; their values cannot be changed after they
 * are created. String buffers support mutable strings.
 * Because String objects are immutable they can be shared. For example:
 * 
 *     String str = "abc";
 * 

 * is equivalent to:
 * 
 *     char data[] = {'a', 'b', 'c'};
 *     String str = new String(data);
 * 

 * Here are some more examples of how strings can be used:
 * 
 *     System.out.println("abc");
 *     String cde = "cde";
 *     System.out.println("abc" + cde);
 *     String c = "abc".substring(2,3);
 *     String d = cde.substring(1, 2);
 * 
 * 

 * The class String includes methods for examining
 * individual characters of the sequence, for comparing strings, for
 * searching strings, for extracting substrings, and for creating a
 * copy of a string with all characters translated to uppercase or to
 * lowercase. Case mapping is based on the Unicode Standard version
 * specified by the {@link java.lang.Character Character} class.
 * 

 * The Java language provides special support for the string
 * concatenation operator ( + ), and for conversion of
 * other objects to strings. String concatenation is implemented
 * through the StringBuilder(or StringBuffer)
 * class and its append method.
 * String conversions are implemented through the method
 * toString, defined by Object and
 * inherited by all classes in Java. For additional information on
 * string concatenation and conversion, see Gosling, Joy, and Steele,
 * The Java Language Specification.
 *
 * 
 Unless otherwise noted, passing a null argument to a constructor
 * or method in this class will cause a {@link NullPointerException} to be
 * thrown.
 *
 * 
A String represents a string in the UTF-16 format
 * in which supplementary characters are represented by surrogate
 * pairs (see the section Unicode
 * Character Representations in the Character class for
 * more information).
 * Index values refer to char code units, so a supplementary
 * character uses two positions in a String.
 * 
The String class provides methods for dealing with
 * Unicode code points (i.e., characters), in addition to those for
 * dealing with Unicode code units (i.e., char values).
 *
 * @author  Lee Boynton
 * @author  Arthur van Hoff
 * @author  Martin Buchholz
 * @author  Ulf Zibis
 * @see     java.lang.Object#toString()
 * @see     java.lang.StringBuffer
 * @see     java.lang.StringBuilder
 * @see     java.nio.charset.Charset
 * @since   JDK1.0
 */

好啦，这就是java的帮助文档…英语不好的童鞋可以使用有道翻译哦~