❤❤❤ HASHMAP ❤❤❤

HashMap store items in "key/value". Key and value will be of any data type can access HashMap's value with a specific key.

The picture is more information:

Key in HashMap can be null and can have more and more null value.

Declaration of Class HashMap:

public class HashMap<K,V> extends AbstractMap<K,V>
    implements Map<K,V>, Cloneable, Serializable

In there:

K: is data type of Key
V: is data type of mapped value

Initialization HashMap

import java.util.HashMap;
// Declared HashMap named mapObject
// has key is Integer and value is HashMapObject
 Map<Integer, HashMapObject> mapObject = new HashMap<>();