Java hashmap键值迭代器

Question

I have a hashmap when i am printing this hashmap the output is like this

{KEY_CH_UP=KEY_CH_UP, KEY_PANEL_CH_UP=KEY_PANEL_CH_UP, KEY_7=KEY_7, KEY_6=KEY_6, KEY_5=null}

Now i want to get all the keys which is having

values == null ;

Answer 1

Iterate over the like below and check if the value is null :

Map<String, String> map = new HashMap<String, String>();
        for(Map.Entry<String, String> en: map.entrySet()){
            if(en.getValue()==null){
                System.out.println(en.getKey());
            }
        }