HashMap in Java

    -What is HashMap:

      A HashMap has value and  key. store value based on Key. HasMap implements the Map interface and extends AbstractMap class.
      Allow only one null as key and can contain   multiple null value.
      Also Conatin Order of element.


        HasMap----extend---->AbstractMap----implement---->Map
       
        Now we see how to Put and Retrive value from HashMap.
       
       Example.

            import java.util.*;
              class MapTest{
                       public static void main(String args[]){
 
  HashMap<Integer,String> map=new HashMap<Integer,String>();
 
  map.put(1,"vjp");
  map.put(13,"Vasant");
  map.put(10,"anil");
 
  for(Map.Entry m:map.entrySet()){
  System.out.println(m.getKey()+" "+m.getValue());
  }
  }
}

 

        -How Internally Working.

     Example.