字符串操作

package welcome;public class 字符串操作 {public static void main(String[] args) {// TODO Auto-generated method stub//关于字符串大小的比较String s1 = "abc";String s2 = "abad";System.out.println(s1.compareTo(s2));//访问字符串里的字符System.out.println(s1.charAt(2));//遍历字符串for(int i = 0; i < s1.length(); i++){System.out.println(s1.charAt(i));}System.out.println();//遍历子串String s3 = "012345B67839汉字";System.out.println(s3.substring(2));System.out.println(s3.substring(2, 4));//寻找位置System.out.println(s3.indexOf('4'));System.out.println(s3.indexOf('A'));System.out.println(s3.indexOf("B67"));System.out.println();//寻找第二次出现的‘3’int loc = s3.indexOf('3');System.out.println(s3.indexOf('3',loc+1));System.out.println();//不变的字符串String s4 = "abcd";String s5 = s4.toUpperCase();System.out.println(s4);System.out.println(s5);System.exit(0);    //注意此种避免错误的方法}}