【09】ComparableVS Comparator

看着长得就像 比较的方法

1. Comparable 产生于java.lang ,作用是在类设计的初期使用

　　实现了重载函数 int compareTo(obj)

2.Comparator 产生于java.util ,作用于类设计后 不动源代码,实现的是 比较器

　　实现的重造函数 int compare(obj1,obj2)

排序出生于Collections。sort(obj,(比较器))

package Concurrency.mid;

import leetcoder.ListNode;

import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.Comparator;
import java.util.List;

class person implements Comparable<person>{
    public String  name;
    public int id;
    person(String name ,int id ){
        this.name = name;
        this.id =id ;
    }
    @Override
    public int compareTo(person other){
        return this.id < other.id ? -1:1;
    }
    @Override
    public String toString(){
        return "name  "+ this.name+"  id  "+id;
    }

}



class student{
    public String  name;
    public int id;
    student(String name ,int id ){
        this.name = name;
        this.id =id ;
    }
    @Override
    public String toString(){
        return "name  "+ this.name+"  id  "+id;
    }
}
class ComparatorStudent implements Comparator<student>{
    @Override
    public int compare(student s1,student s2){
        return s1.id < s2.id?-1:1;
    }
}





public class compareTest {
    public static void main(String []arg){
        List<person> list=  new ArrayList<person>();
        list.add(new person("4",4));
        list.add(new person("2",2));
        list.add(new person("1",1));
        list.add(new person("3",3));


        System.out.println(list);
        Collections.sort(list);
        System.out.println(list);


        List<student> list2=  new ArrayList<>();
        list2.add(new student("4",4));
        list2.add(new student("2",2));
        list2.add(new student("1",1));
        list2.add(new student("3",3));

        System.out.println(list2);
        ComparatorStudent comparatorStudent = new ComparatorStudent();
        Collections.sort(list2,comparatorStudent);
        System.out.println(list2);





    }
}