java 集合中怎么将元素倒序排列

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

public class Test {

public static void main(String[] args) {

ArrayList<String> a = new ArrayList<String>();

a.add("sui yue weu ");
a.add("guang hui sui yue ");
a.add("hai kuo tian kong");

Collections.reverse(a);// 将ArrayLista中的元素进行倒序

for (String str : a)
System.out.println(str);

}

}

方法一：实现Comparable接口排序package collsort.comparable;
package com.cvicse.sort.comparable;

public class Cat implements Comparable<Cat> {
private int age;
private String name;

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

public int getAge() {
return age;
}

public void setAge(int age) {
this.age = age;
}
......
public int compareTo(Cat o) {
return this.getAge() -