Java中的2种集合排序方法介绍

直接上代码：

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



public class CollectionsSort {
	public static void main(String[] args) {
		// method1();测试第一个方法
		method2();// 测试第二个方法
	}

	public static void method1() {
		List list = new ArrayList();
		Cat c = new Cat("a", 10);
		list.add(c);
		c = new Cat("b", 20);
		list.add(c);
		c = new Cat("c", 3);
		list.add(c);
		// 升序排列输出
		Collections.sort(list);
		System.out.println(list);
		// 降序排列输出
		Collections.sort(list, Collections.reverseOrder());
		System.out.println(list);
	}

	public static void method2() {
		List list = new ArrayList();
		Cat c = new Cat("a", 10);
		list.add(c);
		c = new Cat("b", 20);
		list.add(c);
		c = new Cat("c", 3);
		list.add(c);
		Comparator catComparator = new Cat();
		// 升序排列输出
		Collections.sort(list, catComparator);
		System.out.println(list);
		// 降序排列输出
		catComparator = Collections.reverseOrder(catComparator);
		Collections.sort(list, catComparator);
		System.out.println(list);
	}
}

class Cat implements Comparable, Comparator {
	private int age;
	private String name;

	public Cat() {
	}

	public Cat(String name, int age) {
		this.age = age;
		this.name = name;
	}

	public int getAge() {
		return this.age;
	}

	public String getName() {
		return this.name;
	}

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

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

	// 实现了Comparable接口，不要重写该方法
	@Override
	public int compareTo(Cat o) {
		// TODO Auto-generated method stub
		return this.age - o.age;
	}

	@Override
	public String toString() {
		// TODO Auto-generated method stub
		return "名字：" + getName() + ",年龄：" + getAge();
	}

	// 实现了Comparator接口，需要重写该方法
	@Override
	public int compare(Cat o1, Cat o2) {
		// TODO Auto-generated method stub
		return o1.getAge() - o2.getAge();
	}

}