Java集合複習Collection（2）添加一組元素

標籤：extends   調整   類型   說明   lis   底層實現   operation   參數說明   pow   

 1 import java.util.*; 2 class Snow{} 3 class Powder extends Snow{} 4 class Crusty extends Snow{} 5 class Slush extends Snow{} 6  7 class Light extends Powder {} 8 class Heavy extends Powder {} 9 10 11 public class AddingGroups {12 13     public static void main(String[] args) {14 15         Collection<Integer> collection = new ArrayList<Integer>(Arrays.asList(1,2,3));16         Integer[] moreInts = {4,5,6};17         //Arrays.asList 顧名思義，傳進去一個數組，搞出來一個List。數群組轉換為List18         collection.addAll(Arrays.asList(moreInts));19         Collections.addAll(collection, 7);//可變參數列表20         21         /* Arrays.asList()的底層實現是用數組，因此不能調整尺寸。所以運行時會出現UnsupportedOperationException22         List list = Arrays.asList(1,2,3);23         list.add(4);24         System.out.println(list);25         */26         System.out.println(collection);27         28         List<Snow> snow1 = Arrays.asList(new Powder(),new Slush(),new Crusty());29         30         List<Snow> snow2 = Arrays.asList(new Light(),new Heavy());31         32 //        Collections.addAll(snow2);33         34         List<Snow> snow3 = new ArrayList<Snow>();35         36         Collections.addAll(snow3, new Light(),new Heavy());37         38         //顯式型別參數說明39         List<Snow> snow4 = Arrays.<Snow>asList(new Light(),new Heavy());40         41         42     }43 44 }

 

Java集合複習Collection（2）添加一組元素