map集合增强for循环遍历后输出文本

 1 import java.io.BufferedWriter;
 2 import java.io.FileWriter;
 3 import java.io.IOException;
 4 import java.util.HashMap;
 5 import java.util.Map;
 6 
 7 public class mapfor {
 8 
 9 
10     public static void main(String[] args) throws IOException {
11         Map<String, Integer> mp = new HashMap<>();
12         mp.put("张三", 20);
13         mp.put("李四", 21);
14         mp.put("王二", 22);
15         mp.put("李五", 23);
16         //创建字符缓冲输出流对象,构造方法中绑定字符输出流
17         BufferedWriter bw = new BufferedWriter(new FileWriter("10_IO\\789.txt"));
18 
19         String line;
20         //遍历HashMap集合,获取每一个键值对
21         for (String key : mp.keySet()) {//相当于set<String> ks=mp.keySet();mp.keySet()是所有键的集合
22 
23             Integer value = mp.get(key);
24 //            System.out.println(key+"="+value);
25             line = key+"="+value;
26             bw.write(line);
27             bw.newLine();//每次输出时换行
28 
29 //        System.out.println(key + "=" + mp.get(key));
30         }
31         bw.close();
32     }
33 
34 }