集合 

 1 package com.Lucky;
 2 
 3 import java.util.ArrayList;
 4 import java.util.Iterator;
 5 
 6 /**
 7  *    集合：  Collection[接口]  与  Map[接口]
 8  *
 9  *    Collection:  List 与 Set 与 Queue
10  *
11  *     List:    ArrayList    LinkedList
12  *     Set:     HashSet      LinkedHashSet   TreeSet
13  *     Queue:                 LinkedList
14  *
15  *
16  *
17  *     Map:     HashMap  与 TreeMap 与 LinkedHashMap
18  *
19  *
20  */
21 public class ListRemark {
22 
23     public static void main(String[] args) {
24         ArrayList arrayList=new ArrayList();
25         arrayList.add(10);
26         arrayList.add(20);
27         arrayList.add(5);
28         arrayList.add(50);
29 
30 
31               //获取集合里面的数据
32         System.out.println("--------1.for循环遍历----------------");
33         System.out.print("[");
34         for (int i = 0; i < arrayList.size(); i++) {
35            if(i==arrayList.size()-1){
36                System.out.print(arrayList.get(i));
37            }else {
38                System.out.print(arrayList.get(i)+",");
39            }
40         }
41         System.out.println("]");
42 
43 
44 
45 
46 
47 
48         System.out.println("--------2.高级for遍历----------------");
49         System.out.print("[");
50         for (Object obj:arrayList) {
51             System.out.print(obj+",");
52         }
53         System.out.println("]");
54 
55 
56         System.out.println("--------3.迭代器遍历----------------");
57         Iterator iterator= arrayList.iterator();
58         System.out.print("[");
59          while (iterator.hasNext()){
60              System.out.print((int)iterator.next()+",");
61          }
62         System.out.println("]");
63 
64 
65         System.out.println("--------4.lambda遍历----------------");
66         System.out.print("[");
67          arrayList.forEach((elem)->System.out.print(elem+" "));
68         System.out.println("]");
69 
70     }
71 
72 
73 }

 

posted @ 2022-12-12 08:31  唯易人生  阅读(86)  评论(0)    收藏  举报