Comparable与Comparator区别

Dear 丶 2022-02-23 04:40 314阅读 0赞

个人感觉没有什么区别，只是Comparable的compareTo方法为自然比较法，而Comparator要重写compare方法

### Comparable ###

package com.example.demo;
    
    /**
     * @Author: 大鸡腿
     * @Date: 2019/4/6 15:46
     * @Version 1.0
     */
    public class Test1 implements Comparable<Test1>{
    
        String id;
    
        public String getId() {
            return id;
        }
    
        public void setId(String id) {
            this.id = id;
        }
    
        @Override
        public int compareTo(Test1 o) {
            return this.id.compareTo(o.getId());
        }
    }

### Comparator ###

package com.example.demo;
    
    import java.util.Comparator;
    
    /**
     * @Author: 大鸡腿
     * @Date: 2019/4/6 15:46
     * @Version 1.0
     */
    public class Test2 implements Comparator<Test2> {
        private String id;
    
        public String getId() {
            return id;
        }
    
        public void setId(String id) {
            this.id = id;
        }
    
        @Override
        public int compare(Test2 o1, Test2 o2) {
            return o1.getId().compareTo(o2.getId());
        }
    }

package com.example.demo;
    
    import java.util.ArrayList;
    import java.util.Collections;
    import java.util.List;
    
    /**
     * @Author: 大鸡腿
     * @Date: 2019/4/6 15:55
     * @Version 1.0
     */
    public class Test {
    
        public static void main(String[] args) {
            List<Test1> list1=new ArrayList<Test1>();
            List<Test2> list2=new ArrayList<Test2>();
            Test1 t1=new Test1();
            Test1 t2=new Test1();
            t1.setId("1");
            t2.setId("2");
            System.out.println(t1.compareTo(t2));
            /*for(int i=0;i<15;i++){
                int a= (int) (Math.random()*100);
                //System.out.println(a);
                Test1 t1=new Test1();
                Test2 t2=new Test2();
                t1.setId(String.valueOf(a));
                t2.setId(String.valueOf(a));
                list1.add(t1);
                list2.add(t2);
            }
            Collections.sort(list1);
            Collections.sort(list2,new Test2());
            System.out.println("t1开始遍历");
            for(Test1 t:list1){
                System.out.println(t.getId());
            }
            System.out.println("t2开始遍历");
            for(Test2 t:list2){
                System.out.println(t.getId());
            }*/
        }
    
    }

调用的时候，如果是实现了Comparable直接Collections.sort(list1)不用再添加后面的一个排序类的参数

而实现Comparator，需要再Collections.sort(list2,new Test2());