map集合增强for循环遍历后输出文本

import java.io.BufferedWriter;
import java.io.FileWriter;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;

public class mapfor {


    public static void main(String[] args) throws IOException {
        Map<String, Integer> mp = new HashMap<>();
        mp.put("张三", 20);
        mp.put("李四", 21);
        mp.put("王二", 22);
        mp.put("李五", 23);
        //创建字符缓冲输出流对象,构造方法中绑定字符输出流
        BufferedWriter bw = new BufferedWriter(new FileWriter("10_IO\\789.txt"));

        String line;
        //遍历HashMap集合,获取每一个键值对
        for (String key : mp.keySet()) {//相当于set<String> ks=mp.keySet();mp.keySet()是所有键的集合

            Integer value = mp.get(key);
//            System.out.println(key+"="+value);
            line = key+"="+value;
            bw.write(line);
            bw.newLine();//每次输出时换行

//        System.out.println(key + "=" + mp.get(key));
        }
        bw.close();
    }

}