String比较

String比较

通过下面方法：
1. ==
2. equals
3. compareTo

package com.mifeng.test;public class ReplaceDemo {    public static void main(String[] args){        String str = "abc";        String str2 = str.replace("a", "a");        System.out.println(str2);        if(str == str2){            System.out.println("==");        }else{            System.out.println("!=");        }        if(str.equals(str2)){            System.out.println("equals");        }else{            System.out.println("not equals");        }        String s1 = "abd";        String s2 = "abd";        if(s1 == s2){            System.out.println("s1==s2");        }else{            System.out.println("s1!=s2");        }        if(s1.equals(s2)){            System.out.println("s1 equals s2");        }else{            System.out.println("s1 not equals s2");        }        System.out.println("---------------------");        String s3 = "abr";        String s4 = new String("abr");        if(s3 == s4){            System.out.println("s3==s4");        }else{            System.out.println("s3!=s4");        }        if(s3.equals(s4)){            System.out.println("s3 equals s4");        }else{            System.out.println("s3 not equals s4");        }    }}