字符串的比较

public class Jduge {public static void main(String[] args) {String s1="student";String s2="student";String s3  = new String("student");if(s1.equals(s3)){System.out.println("equals");}else{System.out.println("not equals");}if(s1==s2){System.out.println("equals");}else{System.out.println("not equals");}if(s1==s3){System.out.println("equals");}else{System.out.println("not equals");}}}

运行结果：

equals
equals
not equals

原理：equals比较的字符串的内容，==比较的是字符串的地址