遍历Map集合三种方式

public static void main(String[] args) {
    
    HashMap<String, String> map = new HashMap<>();
    map.put("1","a");
    map.put("2","b");
    map.put("3","c");
   
    //第一种方式:keySet
    Set<String> keySet = map.keySet();
    for (String s : keySet) {
        String value = map.get(s);
        System.out.println(s+"="+value);
    }

    //第二种遍历方式:entrySet
    Set<Map.Entry<String, String>> entries = map.entrySet();
    for (Map.Entry<String, String> entry : entries) {
        String key = entry.getKey();
        String value = entry.getValue();
        System.out.println(key+"="+value);
    }

    //第三种方式:lambda
    map.forEach((String key,String value)->{
        System.out.println(key+"="+value);
    });

}