第十二条： Comparable和Comparator

骑猪看日落 2022-07-15 14:17 163阅读 0赞

一个是对于自定义对象内部进行排序， 一个是通过在外部进行排序。  其他的区别并不是很大， 但是感觉写在外部的方式，扩展性和易读性都相对好一些。 具体列子代码如下：

package cn.stu;
    
    
    public class Student implements Comparable{
    	
    	public  String  name;
    	public  double  score; 
    
    	
    	@Override
    	public int compareTo(Object other) {
    		
    		if(other instanceof Student){
    			Student stu = (Student)other;
    			if(this.score > stu.score){
    				return 1; 
    			}else if(this.score < stu.score){
    				return -1; 
    			}
    		}
    		return 0;
    	}
    	
    	
    	@Override
    	public String toString() {
    		 
    		return name+"分数--->"+score;
    	}
    	
    	
    }

package cn.stu;
    
    import java.util.Comparator;
    
    public class Worker{
    	
    	public String name;
    	public double price;
    	
    	 
    	
    	@Override
    	public String toString() {
    		 
    		return  "名字："+name+",工资---->"+price;
    	}
    
    }

package cn.stu;
    
    import java.util.ArrayList;
    import java.util.Collections;
    import java.util.Comparator;
    import java.util.List;
    
    public class Main {
    
    	 
    	@SuppressWarnings("unchecked")
    	public static void main(String[] args) {
    		 
    		Student stu_A = new Student();
    		stu_A.name = "小强";
    		stu_A.score = 50; 
    		 
    		Student stu_B = new Student();
    		stu_B.name = "小发";
    		stu_B.score = 80; 
    
    		int result = stu_A.compareTo(stu_B);
    		System.out.println(result);
    		
    		List<Student> stuList = new ArrayList<Student>();
    		Student entity = null;
    		
    		List<Worker> workerList = new ArrayList<Worker>();
    		Worker worker = null;
    		
    		for(int  i = 0; i<10; i++){
    			
    			  entity = new Student();
    			  entity.name = i+"小笑"; 
    			  entity.score = (int)(Math.random()*100);
    			  stuList.add(entity);
    			  
    			  worker = new Worker();
    			  worker.name = i + "小凯";
    			  worker.price = (int)(Math.random()*10000);
    			  workerList.add(worker);
    		}
    		 
    		Comparator comparator = new Comparator<Worker>() {
    
    			@Override
    			public int compare(Worker o1, Worker o2) {
    			 
    				return o1.price > o2.price ? -1 :(o1.price == o2.price ? 0 : 1);
    			}
    			
    			
    		};
    		Collections.sort(stuList);
    		// entity.compareTo(other)
    		
    		Collections.sort(workerList, comparator);
    		// comparator.compare(o1, o2) 单个比较。
    		
    		for(int i = 0; i<stuList.size(); i++){
    			System.out.println(stuList.get(i));
    		}
    		
    		for(int i = 0; i<workerList.size(); i++){
    			System.out.println(workerList.get(i));
    		}
    		 
    	}
    
    }

运行结果如下：

\-1  
2小笑分数--->0.0  
3小笑分数--->27.0  
4小笑分数--->51.0  
7小笑分数--->55.0  
8小笑分数--->70.0  
1小笑分数--->85.0  
9小笑分数--->93.0  
0小笑分数--->97.0  
6小笑分数--->97.0  
5小笑分数--->98.0  
名字：5小凯,工资---->9646.0  
名字：2小凯,工资---->9445.0  
名字：3小凯,工资---->9123.0  
名字：7小凯,工资---->5825.0  
名字：9小凯,工资---->4973.0  
名字：1小凯,工资---->3553.0  
名字：8小凯,工资---->3152.0  
名字：6小凯,工资---->2559.0  
名字：0小凯,工资---->290.0  
名字：4小凯,工资---->134.0