Java：遍历HashMap的常用方法

1、entrySet

import java.util.HashMap;
import java.util.Map;

public class demo {
    public static void main(String[] args) {
        Map<String, String> map = new HashMap<>();
        map.put("name", "Tom");
        map.put("age", "23");
        map.put("school", "pku");

        for(Map.Entry<String, String> entry: map.entrySet()){
            System.out.println(entry.getKey() + "=>" + entry.getValue());
        }

    }
}

输出结果

school=>pku
name=>Tom
age=>23

2、keySet

import java.util.HashMap;
import java.util.Map;

public class demo {
    public static void main(String[] args) {
        Map<String, String> map = new HashMap<>();
        map.put("name", "Tom");
        map.put("age", "23");
        map.put("school", "pku");

        for (String key : map.keySet()) {
            System.out.println(key + "=>" + map.get(key));
        }

    }
}

输出结果

school=>pku
name=>Tom
age=>23

3、forEach

import java.util.HashMap;
import java.util.Map;

public class demo {
    public static void main(String[] args) {
        Map<String, String> map = new HashMap<>();
        map.put("name", "Tom");
        map.put("age", "23");
        map.put("school", "pku");

        // 1.8
        map.forEach((key, value) -> {
            System.out.println(key + "=>" + value);
        });

    }
}

输出结果

school=>pku
name=>Tom
age=>23

参考
​​​Java 中九种 Map 的遍历方式，你一般用的是哪种呢？​​