Comparable与Comparator

1、Comparable接口

import java.util.Arrays;
//实现Comparable接口，重写compareTo方法
public class User implements Comparable<User>{
	private int id;
	private String name;
	private int age;
	public User(){}
	public User(int id,String name,int age){
		this.id = id;
		this.name = name;
		this.age = age;
	}
	@Override
	public int compareTo(User o) {
		
		return this.getAge() - o.getAge();
	}
	//getters/setters
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	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;
	}
	//测试
	public static void main(String[] args) {
		User[] users = new User[4];
		users[0] = new User(1,"Array",10);
		users[1] = new User(2,"List",9);
		users[2] = new User(3,"Vector",12);
		users[3] = new User(4,"Set",7);
		//进行排序
		Arrays.sort(users);
		//查看结果
		for(User u : users){
			System.out.println(u.getAge() + " - " + u.getId() + " - " + u.getName());
		}
	}
}

2、Comparator类

import java.util.Arrays;
import java.util.Comparator;
public class User{
	private int id;
	private String name;
	private int age;
	public User(){}
	public User(int id,String name,int age){
		this.id = id;
		this.name = name;
		this.age = age;
	}
	//getters/setters
	public int getId() {
		return id;
	}
	public void setId(int id) {
		this.id = id;
	}
	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;
	}
	//测试
	public static void main(String[] args) {
		User[] users = new User[4];
		users[0] = new User(1,"Array",10);
		users[1] = new User(2,"List",9);
		users[2] = new User(3,"Vector",12);
		users[3] = new User(4,"Set",7);
		//引用比较器，排序
		Arrays.sort(users,new UserComparator());
		//查看结果
		for(User u : users){
			System.out.println(u.getAge() + " - " + u.getId() + " - " + u.getName());
		}
	}

}
//创建比较器类，设置排序规则
class UserComparator implements Comparator<User>{
	@Override
	public int compare(User o1, User o2) {
		return o1.getAge() - o2.getAge();
	}	
}