从 map 检索密钥列表

Question

HashMap<String,String> map=new HashMap<>();
        map.put("name","x");
        map.put("value", "yes");
HashMap<String,String> map1=new HashMap<>();
        map1.put("name","y");
        map1.put("value", "yes");

I want how to get values for specific key i want the solution like(x,y)

Answer 1

In order to get hashMap's keys set, you can call HashMap#keySet()

In order to get HashMap's values set, you can call hashMap#values()

Now, if you wanna get a value of a specific key, you can do it with HashMap#entrySet(), it returns a set of every key with relative value, then check egery one with an if-statement and you've done

doc

Answer 2

Map has the method "keySet()" for getting Set of keys, for getting List from Set you can use ArrayList's a constructor:

List<String> result = new ArrayList<>(map.keySet());

for getting element from List:

for(String name: result){
   if(name.equals("someName")){
   System.out.println(name);
  }
 }

Answer 3

Please note that if you are using String as key values, then you need to include code to eliminate duplicate string values from map. That is why having String as key is not a good Idea. Otherwise, write specific Code to eliminate duplicate String values from hashmap by Iterating key values from Hashmap(KeySet). Construct one more Hashmap and push values from both maps into another map. Once again, Please be careful about duplicate x values in the third map(Just as stated above, write code for eliminating duplicate x values).