1 import java.util.HashMap;
2 import java.util.Iterator;
3 import java.util.Map;
4
5 /**
6 * @Author：KoVaVo
7 * @Version：1.0.0
8 * @Description：
9 */
10 public class HashMapTest {
11 public static void main(String[] args) {
12 //hashMap的几种便利方式
13 HashMap<Integer, String> hashMap = new HashMap<Integer, String>();
14 hashMap.put(1,"1");
15 hashMap.put(2,"2");
16 hashMap.put(3,"3");
17 System.out.println("=====keyset=====");
18 long l = System.currentTimeMillis();
19 for (int key : hashMap.keySet()) {
20 System.out.println(key+"..."+hashMap.get(key));
21 }
22 System.out.println(l-System.currentTimeMillis());
23 System.out.println("=====iterator=====");
24 l=System.currentTimeMillis();
25 Iterator<Map.Entry<Integer, String>> iterator = hashMap.entrySet().iterator();
26 while (iterator.hasNext()){
27 Map.Entry<Integer,String> next = iterator.next();
28 System.out.println(next.getValue()+"...iterator");
29 }
30 System.out.println(l-System.currentTimeMillis());
31 System.out.println("=====entryset=====");
32 l=System.currentTimeMillis();
33 for (Map.Entry<Integer, String> entry : hashMap.entrySet()) {
34 System.out.println(entry.getValue());
35 }
36 System.out.println(l-System.currentTimeMillis());
37 }
38 }
