HashMap vs Hashtable vs HashSet

  Here I am going to explain difference between HashMap vs HasTable vs HashSet 

HashMap 

     HashMap accepts key-value pair,It allows null value for both key and Value and HashMap is Unsynchronized.

  HashMap<String,String> hashmap=new HashMap<String,String>();

  hashmap.put("1","Dhina");
  hashmap.put("2",null);

HasTable 

 HasTable accepts key-value pair,It didn't allows null value for both key and Value and HasTable is Synchronized.


  HasTable <String,String> hashtable=new HasTable <String,String>();

  hashtable.put("1","Dhina");
  hashtable.put("2","Karan");


HashSet 

     HashSet does not allow duplicate values. It provides add method rather put method. You also use its contain method to check whether the object is already available in HashSet . HashSet can be used where you want to maintain a unique list.


  HashSet<String> set= new HashSet<String>();
  set.add ("DH");
  set.add ("IN");