import  java.util.*;

 public   class  UseHashMap{
	 public   static   void  main(String[] args) {
				
		/* Use of HashMap
		 * Begin
		 */
		String aa= "INDIA";
		HashMap hashmap =  new  HashMap();
		
		//To add elements in the HashMap
		hashmap.put("one", new  Integer( 1 ));
		hashmap.put("two", null );
		hashmap.put("three","THREE");
		hashmap.put("four",aa);
		
		//To see the size and to check whether HashMap is empty or not
		System.out.println("The size of HashMap = "+hashmap.size());
		System.out.println("If hashmap empty = "+hashmap.isEmpty());
		
		System.out.println("The elements of HashMap are");
		Set set= hashmap.keySet();
		Iterator iter = set.iterator();
		 int  i= 1 ;
		 while (iter.hasNext()){
			System.out.println("   "+i+") "+hashmap.get(iter.next()));
			i++;
		}
		
		// Checks whether this key/value is present in the HashMap or not
		System.out.println("Contains this \"one\" Key  ="+hashmap.containsKey("one")); 
		System.out.println("Contains this \"five\" Key  ="+hashmap.containsKey("five")); 
		System.out.println("Contains this \"aa\" Value  ="+hashmap.containsValue(aa)); 
		System.out.println("Contains this \"new Integer(6)\" Value  ="+hashmap.containsValue( new  Integer( 6 )));

		//The value for the key specified
		System.out.println("The value for the \"three\" key  ="+hashmap.get("three"));
		
		//Remove the value for the sepcified key
		hashmap.remove("two");
		System.out.println("The size of HashMap has reduced by one");
		System.out.println("The size of HashMap  = "+hashmap.size());
		System.out.println("The values of HashMap are ="+hashmap.values());
		
		//Remove all the elements from the HashMap
		hashmap.clear();
		System.out.println("If hashmap empty = "+hashmap.isEmpty());

		/* End of HashMap*/
			
	}
}