Comparable接口的用法和实现

Comparable接口的用法和实现

Comparable接口中只有一个方法，
   public int compareTo(Object obj);
   该方法：
          返回0  表示this==obj;
          返回正整数表示  this>obj;
          返回负数表示this<obj
  实现了Comparable接口的类通过实现了compareTo方法从而确定该类对象的排序方式

下面是java中代码的实现方式：

import java.util.Collections;import java.util.ArrayList;import java.util.List;public class TestComparable {public static void main(String[] args) {List<Student> list=new ArrayList<Student>();Student stu1=new Student(1,"张三",100);Student stu2=new Student(3,"张四",80);Student stu3=new Student(2,"张五",90);list.add(stu1);list.add(stu2);list.add(stu3);System.out.println(list);Collections.sort(list);System.out.println(list);}}class Student implements Comparable<Student>{int id;String name;int score;public Student(int id,String name,int score){super();this.id=id;this.name=name;this.score=score;}public String toString(){return id+" "+name+score;}public int compareTo(Student o){if(this.score>o.score){return 1;}else if(this.score<o.score){return -1;}else{return 0;}}}