A HashMap is a subclass of AbstractMap class and it is used to store key & value pairs. Each key is mapped to a single value in the map and the keys are unique. It means we can insert a key only once in a map and duplicate keys are not allowed, but the value can be mapped to multiple keys. We can add the elements using the put() method of HashMap class and iterate the elements using the Iterator interface.
Syntax
public V put(K key, V value)
Example
import java.util.*; import java.util.Map.*; public class HashMapTest { public static void main(String[] args) { HashMap map = new HashMap(); // adding the elements to hashmap using put() method map.put("1", "Adithya"); map.put("2", "Jai"); map.put("3", "Chaitanya"); map.put("4", "Krishna"); map.put("5", "Ramesh"); if(!map.isEmpty()) { Iterator it = map.entrySet().iterator(); while(it.hasNext()) { Map.Entry obj = (Entry)it.next(); System.out.println(obj.getValue()); } } } }
Output
Adithya Jai Chaitanya Krishna Ramesh