Java集合复习Collection

import java.util.*;
class Snow{}
class Powder extends Snow{}
class Crusty extends Snow{}
class Slush extends Snow{}

class Light extends Powder {}
class Heavy extends Powder {}


public class AddingGroups {

    public static void main(String[] args) {

        Collection<Integer> collection = new ArrayList<Integer>(Arrays.asList(1,2,3));
        Integer[] moreInts = {4,5,6};
        //Arrays.asList 顾名思义，传进去一个数组，搞出来一个List。数组转换为List
        collection.addAll(Arrays.asList(moreInts));
        Collections.addAll(collection, 7);//可变参数列表
        
        /* Arrays.asList()的底层实现是用数组，因此不能调整尺寸。所以运行时会出现UnsupportedOperationException
        List list = Arrays.asList(1,2,3);
        list.add(4);
        System.out.println(list);
        */
        System.out.println(collection);
        
        List<Snow> snow1 = Arrays.asList(new Powder(),new Slush(),new Crusty());
        
        List<Snow> snow2 = Arrays.asList(new Light(),new Heavy());
        
//        Collections.addAll(snow2);
        
        List<Snow> snow3 = new ArrayList<Snow>();
        
        Collections.addAll(snow3, new Light(),new Heavy());
        
        //显式类型参数说明
        List<Snow> snow4 = Arrays.<Snow>asList(new Light(),new Heavy());
        
        
    }

}