Random r = new Random();
		List<Hero> heroes = new ArrayList<>();
		for (int i = 0; i < 10; i++) {
			heroes.add(new Hero("Hero-" + i, r.nextFloat(), r.nextFloat(), r.nextInt(100)));
		}
		System.out.println(heroes);
		System.out.println("排序后");
		Collections.sort(heroes);
		System.out.println(heroes);
		TreeSet<Integer>set =  new TreeSet<>(new Comparator<Integer>() {

			@Override
			public int compare(Integer o1, Integer o2) {
				return o2-o1;
			}
		});
		for (int i = 0; i < 10; i++) {
			set.add(r.nextInt(10));
		}
		System.out.println(set);

// Item
public class Item implements Comparable<Item>{
	...
	public String toString() {
		return "Item [name = " + name + ", price = " + price + "],\r\n";
	} 
	
	@Override
	public int compareTo(Item o) {
		// 比较...
		if(price < o.price)
			return 1;
		else 
			return -1;
	}
	...
}

// TestCollection  main
Random r = new Random();
List<Item> items = new ArrayList<>(); 

for(int i = 0; i < 10; i++) {
	// 通过随机值实例化items的price
	int e = (int)(Math.random()*(100 - 1 + 1) + 1);
	items.add(new Item("item " + i, r.nextInt(100)));
} 
System.out.println("初始化后的集合：");
System.out.println(items);

// .....
Collections.sort(items);       

System.out.println("排序后的集合：");
System.out.println(items);


console:
初始化后的集合：
[Item [name = item 0, price = 0],
, Item [name = item 1, price = 45],
, Item [name = item 2, price = 17],
, Item [name = item 3, price = 97],
, Item [name = item 4, price = 62],
, Item [name = item 5, price = 44],
, Item [name = item 6, price = 86],
, Item [name = item 7, price = 75],
, Item [name = item 8, price = 35],
, Item [name = item 9, price = 99],
]
排序后的集合：
[Item [name = item 9, price = 99],
, Item [name = item 3, price = 97],
, Item [name = item 6, price = 86],
, Item [name = item 7, price = 75],
, Item [name = item 4, price = 62],
, Item [name = item 1, price = 45],
, Item [name = item 5, price = 44],
, Item [name = item 8, price = 35],
, Item [name = item 2, price = 17],
, Item [name = item 0, price = 0],
]	

 Comparator<Integer> c=new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                return o2-o1;
            }
        };
        Set<Integer> treeset=new TreeSet<>(c);
        for(int i=0;i<10;i++){
             treeset.add(i);
        }
        System.out.println(treeset);


6.

 Random r=new Random();
        List<Item> item =new ArrayList<>();
        for(int i=0;i<10;i++){
            item.add(new Item("item"+i, r.nextInt(100)));
        }
        System.out.println(item);
        Collections.sort(item);
        System.out.println("排序后");
        System.out.println(item);

 Comparator<Integer> c=new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                return o2-o1;
            }
        };
        Set<Integer> treeset=new TreeSet<>(c);
        for(int i=0;i<10;i++){
             treeset.add(i);
        }
        System.out.println(treeset);

package collection;

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

import base.Item;

public class TestTreeSet {
	/**
	 * 默认情况下，TreeSet中的数据是从小到大排序的，不过TreeSet的构造方法支持传入一个Comparator
 
		public TreeSet(Comparator comparator) 

		通过这个构造方法创建一个TreeSet，使得其中的的数字是倒排序的 
	 * @param args
	 */
	public static void main(String[] args) {
		Comparator<Integer> c = new Comparator<Integer>() {
			@Override
			public int compare(Integer o1, Integer o2) {
				if (o1 >= o2) {
					return -1;
				}
				return 1;
			}
		};
		TreeSet<Integer> ts = new TreeSet<>(c);
		for(int i = 0; i < 10; i++){
			ts.add((int)(Math.random() * 100));
		}
		System.out.println("初始化后的集合");
		System.out.println(ts);
		System.out.println("================================");
		method();
	}
	
	/**
	 * 借助Comparable接口，使Item具备按照价格从高到低排序。
		初始化10个Item,并且用Collections.sort进行排序，查看排序结果 
	 */
	public static void method(){
		List<Item> l = new ArrayList<Item>();
		Random r = new Random();
		for (int i = 0; i < 10; i++) {
			l.add(new Item("item-" + i, r.nextDouble()));
		}
		System.out.println("初始化后的集合");
		System.out.println(l);
		Collections.sort(l);
		System.out.println("按照价格从高到低排序:");
		System.out.println(l);
	}
}