Java中的比较器Comparable、Comparator

参考博客：java学习笔记13--比较器(Comparable、Comparator)

在Java代码中，我们常常会面临需要对集合进行排序的情况，这种情况下我们需要手动的定义Java比较器，告诉程序两个对象如何比较大小。
Java中的比较器分为两种Comparable和Comparator：

• Comparable：实现Comparable接口，并且重写compareTo(T o)方法
• Comparator：实现Comparator接口，并且重写compare()和equals()方法

Comparable实现

class Student implements Comparable<Student>{
    private String name;
    private int age;
    private float score;
    
    public Student(String name,int age,float score){
        this.name = name;
        this.age = age;
        this.score = score;
    }
    
    @Override
    public int compareTo(Student stu) {  //覆写compareTo方法实现排序规则的应用
        if(this.score>stu.score){
            return -1;
        }else if(this.score<stu.score){
            return 1;
        }else{
            if(this.age>stu.age){
                return 1;
            }else if(this.age<stu.age){
                return -1;
            }else{
                return 0;
            }
        }
    }
    
    public String toString(){
        return "姓名："+this.name+", 年龄："+this.age+", 成绩："+this.score;
    }
    
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
    public float getScore() {
        return score;
    }
    public void setScore(float score) {
        this.score = score;
    }
    
    
}
 
public class T {
    public static void main(String[] args) throws Exception{
        Student stu[] = {new Student("张三",22,80f)
                        ,new Student("李四",23,83f)
                        ,new Student("王五",21,80f)};
        
        Arrays.sort(stu);   //进行排序操作
        for (int i = 0; i < stu.length; i++) {
            Student s = stu[i];
            System.out.println(s);
        }
    }
}

Compartor

package com.itmyhome;
 
import java.util.Comparator;
 
public class MyComparator implements Comparator<Student> {  //实现比较器
 
    @Override
    public int compare(Student stu1, Student stu2) {
        // TODO Auto-generated method stub
        if(stu1.getAge()>stu2.getAge()){
            return 1;
        }else if(stu1.getAge()<stu2.getAge()){
            return -1;
        }else{
            return 0;
        }
    }
 
}

class Student {
    private String name;
    private int age;
    
    public Student(String name,int age ){
        this.name = name;
        this.age = age;
    }
    
    public String toString(){
        return "姓名："+this.name+", 年龄："+this.age;
    }
    
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
    public int getAge() {
        return age;
    }
    public void setAge(int age) {
        this.age = age;
    }
}
 
public class T {
    public static void main(String[] args) throws Exception{
        Student stu[] = {new Student("张三",23)
                        ,new Student("李四",26)
                        ,new Student("王五",22)};
        Arrays.sort(stu,new MyComparator());             //对象数组进行排序操作
        
        List<Student> list = new ArrayList<Student>();
        list.add(new Student("zhangsan",31));
        list.add(new Student("lisi",30));
        list.add(new Student("wangwu",35));
        Collections.sort(list,new MyComparator());      //List集合进行排序操作
        
        for (int i = 0; i < stu.length; i++) {
            Student s = stu[i];
            System.out.println(s);
        }
        
        System.out.println("*********");
        
        for (int i=0;i<list.size();i++){
            Student s = list.get(i);
            System.out.println(s);
        }
    }
}

来源：https://www.cnblogs.com/mrnx2004/p/11794219.html