JDK5-增强for循环

Posted 2020-08-17 Joshua

下面的程序演示了增强for循环在数组及集合中的应用：

 1 import java.util.ArrayList;
 2 import java.util.HashMap;
 3 import java.util.HashSet;
 4 import java.util.List;
 5 import java.util.Map;
 6 import java.util.Map.Entry;
 7 import java.util.Set;
 8 
 9 public class Foreach {
10 
11     public static void main(String[] args) {
12         // TODO Auto-generated method stub
13         int[] ints = new int[] { 1, 2, 3 };
14         for (int i : ints)
15             System.out.print(i);
16 
17         List<Integer> list = new ArrayList<Integer>();
18         for (int i = 0; i < 3; i++)
19             list.add(i + 1);
20         for (int i : list)
21             System.out.print(i);
22 
23         Set<Integer> set = new HashSet<Integer>();
24         for (int i = 0; i < 3; i++)
25             set.add(i + 1);
26         for (int i : set)
27             System.out.print(i);
28 
29         Map<Integer, String> map = new HashMap<Integer, String>();
30         for (int i = 0; i < 3; i++)
31             map.put(i + 1, String.valueOf(i + 1));
32         for (Entry<Integer, String> entry : map.entrySet())
33             System.out.print(entry.getKey() + entry.getValue());
34     }
35 }

注意：增强for循环只能够遍历实现了Iteratable接口的对象