public class X{

public static void main(String [] args){

       String names[]=new String[5];

       for(int x=0; x<args.length; x++)

              names[x]=args[x];

      System.out.println(names[2]);

}

}

命令行执行：java X a b后，其输出结果是下面哪一个？

1.  String s1=“a”+“b”;

2.  String s2=new String(s1);

3.  if(s1==s2)

4.      System.out.println(“= = is succeeded”);

5.   if (s1.equals(s2))

6.        System.out.println(“.equals() is succeeded”);

String s1=new String("abc");

String s2=new String("Abc");

if(s1==s2)

         System.out.println(“= = is succeeded”);

if (s1.equals(s2))

        System.out.println(“equals() is succeeded”);

String s1 = "Cat";

String s2 = "Cat";

String s3 = new String("Cat");

System.out.println("s1 == s2 :"+(s1==s2));

 System.out.println("s1 == s3 :"+(s1==s3));

String s1 = "Hello";

s1=s1+"World";

String s = "Y,Kunming,Yunnan";

String[] data = s.split(",", 2);

System.out.println("Name = "+data[0]);

System.out.println("Address = "+data[1]);

String str = "Java study";

char c[]=str.toCharArray();

System.out.println(c.length);

System.out.println(c[c.length-1]);

String s=“abcdef”;

System.out.println(s.charAt(4));

String s="Hello World!";

System.out.println(s.indexOf("or"));

System.out.println(s.indexOf("od",6));

System.out.println(s.lastIndexOf("o"));

String s=“ Java class ”; //整个字符串最左边两个空格，中间一个空格，最右边一个空格

String s="ab4ef56g";

System.out.println(s.replaceAll("\\d","#"));

System.out.println(s.replaceFirst("\\d","#"));

String s="abcdefgh";

System.out.println(s.substring(5));

System.out.println(s.substring(3,6));

String s="abc,def,gh,ijk,swt";

String[] str=s.split(",",3);