java的比较器_java 两种比较器的使用

······两种比较器用法~~~~~~第一种让所比较的类实现comparable接口~~~~~~第二种用匿名内部类构造comparatorpackage com.Compare.test;public class Student implements Comparable{//接口类型int id;String name;@Overridepublic String toString() {//tostring 为了打印结果return "Student [id=" + id + ", name=" + name + "]";}Student(int id,String name){this.id=id;this.name=name;}@Overridepublic int compareTo(Student o) {return id>o.id?1:-1;//记得返回一正一负}}~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~package com.Compare.test;import java.util.ArrayList;import java.util.Collections;import java.util.List;public class test1 {public static void main(String[] args) {List list=new ArrayList<>();//可以排序的才可以这么写list.add(new Student(1,"jiang"));list.add(new Student(3,"jiang"));list.add(new Student(2,"jiang"));System.out.println(list);//排序前Collections.sort(list);System.out.println(list);//排序后}}~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~package com.Compare.test;public class Teacher {int id;String name;public Teacher(int id, String name) {super();this.id = id;this.name = name;}@Overridepublic String toString() {return "Teacher [id=" + id + ", name=" + name + "]";}}~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~package com.Compare.test;import java.util.ArrayList;import java.util.Collections;import java.util.Comparator;import java.util.List;public class test2 {public static void main(String[] args) {List list=new ArrayList<>();Comparator c=new Comparator(){@Overridepublic int compare(Teacher o1, Teacher o2) {return o1.id>o2.id?1:-1;}};list.add(new Teacher(1,"jiang"));list.add(new Teacher(3,"jiang"));list.add(new Teacher(2,"jiang"));System.out.println(list);Collections.sort(list,c);System.out.println(list);}}