使用String

package com.jdk7.chapter5;

public class UseString {
    
    /**
     * 如果源字符串中匹配有个多个目标字符串，则取最后一个的起始索引号
     * @param src
     * @param dest
     */
    public static void findStr(String src, String dest){
        if(dest==null){
            System.out.println("目标字符串不能为空！");
        }
        System.out.println("src.indexOf(dest) = "+src.indexOf(dest));
        System.out.println("src.indexOf(dest, 4) = "+src.indexOf(dest, 4));
        System.out.println("src.lastIndexOf(dest) = "+src.lastIndexOf(dest));
        System.out.println("src.lastIndexOf(dest, 4) = "+src.lastIndexOf(dest, 4));
    }
    
    public static void subStr(String src){
        if(src==null){
            System.out.println("源字符串不能为空！");
        }
        System.out.println("src.substring(2) = "+src.substring(2));
        System.out.println("src.substring(4, 10) = "+src.substring(4, 10));
    }
    
    public static void replaceStr(String src){
        if(src==null){
            System.out.println("源字符串不能为空！");
        }
        System.out.println(src.replace('a', 'i'));
        System.out.println(src.replaceFirst("s", "p"));
        System.out.println(src.replaceAll("s", "y"));
    }
    
    public static void toUpperOrLower(String src){
        if(src==null){
            System.out.println("源字符串不能为空！");
        }
        System.out.println(src.toUpperCase());
        System.out.println(src.toLowerCase());
    }
    
    public static void charAt(String src){
        if(src==null){
            System.out.println("源字符串不能为空！");
        }
        System.out.println("src.charAt(5) = "+src.charAt(5));
        //字符串和字符不能自动进行类型转换，所以没法正常打印
        System.out.println(src.toCharArray());
    }
    
    /**
     * 比较规则为：从第一个字符编码开始比较，如果第一个字符编码比目标字符编码小则返回负数，如果相等则返回0，如果比目标字符编码大则返回正数，
     * 返回的值为字符编码与目标字符编码之差
     * @param src
     * @param dest
     */
    public static void compare(String src,String dest){
        if(src==null || dest==null){
            System.out.println("源字符串或目标字符串不能为空！");
        }
        System.out.println("两个字符串进行比较的结果为： "+src.compareTo(dest));
    }
    
    public static void equals(String src, String dest){
        if(src==null){
            System.out.println("源字符串不能为空！");
        }
//        System.out.println("src.startsWith("T") = "+src.startsWith("T"));
//        System.out.println("src.endsWith("!") = "+src.endsWith("!"));
        System.out.println("src.equals(dest) = "+src.equals(dest));
        System.out.println("src.equalsIgnoreCase(dest) = "+src.equalsIgnoreCase(dest));
    }
    
    public static void startWith(){
        
    }
    
    public static void endWith(){
        
    }
    
    public static void regex(){
        String src = "aab      aaa  bb    ab";
        String pattern = "^[a-zA-Z| ]$";
        System.out.println("src = "+src+"	pattern: "+pattern);
        System.out.println("src匹配pattern = "+src.matches(pattern));
        System.out.println("用一个空格替换第一个连续两位以上的制表符 >"+src.replaceFirst("\s{2,}", " "));
        System.out.println("用一个空格替换所有连续两位以上的制表符 >"+src.replaceAll("\s{2,}", " "));
        
        String[] strA = src.split("\s{2,}");
        System.out.print("以连续制表符分隔后的数组为>");
        for(int i=0;i<strA.length;i++){
            System.out.print(strA[i]+" ");
        }
        System.out.println();
        
        String[] strB = src.split("\s{2,}", 3);
        System.out.print("已连续制表符分隔最多3段的数组为>");
        for(int i=0;i<strB.length;i++){
            System.out.print(strB[i]+" ");
        }
        System.out.println();
    }
    
    
    public static void main(String[] args) {
        String src = "This is a string Object!";
        String dest = "is";
        System.out.println("==============查找String中目标字符串所在索引号==============");
        UseString.findStr(src, dest);
        System.out.println("==============截取String中目标字符串==============");
        UseString.subStr(src);
        System.out.println("==============替换String中的某些字符串==============");
        UseString.replaceStr(src);
        System.out.println("==============将String字符串统一变大写或小写==============");
        UseString.toUpperOrLower(src);
        System.out.println("==============获取String中某个位置的字符==============");
        UseString.charAt(src);
        System.out.println("==============比较源字符串和目标字符串，比较原则从首字符开始比较字符编码，返回结果为字符编码差值==============");
        UseString.compare(src, dest);
        UseString.compare(src, src);
        UseString.compare(src, "A");
        System.out.println("==============比较两个字符串是否相等，分是否区分大小写两种情况==============");
        UseString.equals(src, "esgt");
        UseString.equals(src, "THIS IS A STRING OBJECT!");
        UseString.equals(src, src);
        System.out.println("==============字符串和正则表达式是否匹配，以及使用正则表达是分隔字符串==============");
        UseString.regex();
    }
}

执行结果为：
==============查找String中目标字符串所在索引号==============
src.indexOf(dest) = 2
src.indexOf(dest, 4) = 5
src.lastIndexOf(dest) = 5
src.lastIndexOf(dest, 4) = 2
==============截取String中目标字符串==============
src.substring(2) = is is a string Object!
src.substring(4, 10) =  is a 
==============替换String中的某些字符串==============
This is i string Object!
Thip is a string Object!
Thiy iy a ytring Object!
==============将String字符串统一变大写或小写==============
THIS IS A STRING OBJECT!
this is a string object!
==============获取String中某个位置的字符==============
src.charAt(5) = i
This is a string Object!
==============比较源字符串和目标字符串，比较原则从首字符开始比较字符编码，返回结果为字符编码差值==============
两个字符串进行比较的结果为： -21
两个字符串进行比较的结果为： 0
两个字符串进行比较的结果为： 19
==============比较两个字符串是否相等，分是否区分大小写两种情况==============
src.equals(dest) = false
src.equalsIgnoreCase(dest) = false
src.equals(dest) = false
src.equalsIgnoreCase(dest) = true
src.equals(dest) = true
src.equalsIgnoreCase(dest) = true
==============字符串和正则表达式是否匹配，以及使用正则表达是分隔字符串==============
src = aab      aaa  bb    ab    pattern: ^[a-zA-Z| ]$
src匹配pattern = false
用一个空格替换第一个连续两位以上的制表符 >aab aaa  bb    ab
用一个空格替换所有连续两位以上的制表符 >aab aaa bb ab
以连续制表符分隔后的数组为>aab aaa bb ab 
已连续制表符分隔最多3段的数组为>aab aaa bb    ab