Comparator 与 Comparable之间的差别

以前一直都用Comparable接口来排序直到最近才只知道还有Comparator接口。
2个接口的区别在于一个是在类的内部实现，另外一个是通过外部类来实现
简单通过代码来写下区别
1、Comparator 模式
A、被比较的类

public class User {

	private String name;

	private int age;

	public String getName() {
		return name;
	}

	public void setName(final String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(final int age) {
		this.age = age;
	}

}

B、比较的实现

import java.util.Comparator;

public class UserCompare implements Comparator<User> {

	@Override
	public int compare(final User user1, final User user2) {
		if (user1.getAge() > user2.getAge()) {
			return 1;
		} else if (user1.getAge() < user2.getAge()) {
			return -1;
		} else {
			return 0;
		}
	}
}

2、Comparable模式

public class UserVo implements Comparable<UserVo> {

	private String name;

	private int age;

	public String getName() {
		return name;
	}

	public void setName(final String name) {
		this.name = name;
	}

	public int getAge() {
		return age;
	}

	public void setAge(final int age) {
		this.age = age;
	}

	@Override
	public int compareTo(final UserVo user) {
		if (this.age > user.getAge()) {
			return 1;
		} else if (this.age < user.getAge()) {
			return -1;
		} else {
			return 0;
		}
	}

}

3、Main方法

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

public class Main {
	public static void main(final String args[]) {
		User user1 = new User();
		user1.setName("1");
		user1.setAge(1);
		User user2 = new User();
		user2.setName("2");
		user2.setAge(2);
		UserCompare uc = new UserCompare();
		List<User> array = new ArrayList<User>();
		array.add(user1);
		array.add(user2);
		Collections.sort(array, uc);
		System.out.println("==============Comparator==============");
		for (User user : array) {
			System.out.println(user.getName());
		}
		UserVo userVo1 = new UserVo();
		userVo1.setName("1");
		userVo1.setAge(2);
		UserVo userVo2 = new UserVo();
		userVo2.setName("2");
		userVo2.setAge(1);
		List<UserVo> array1 = new ArrayList<UserVo>();
		array1.add(userVo1);
		array1.add(userVo2);
		Collections.sort(array1);
		System.out.println("==============Comparable==============");
		for (UserVo user : array1) {
			System.out.println(user.getName());
		}
	}
}

4、结果
==============Comparator==============
1
2
==============Comparable==============
2
1