java.util.HashMap class

java.util.HashMap class

java.util.HashMap class

• We can store group of objects in the form of key-value pairs in HashMap object.
• Both key and values are objects only.
• Keys can be unique and values can be duplicate.
• Here group of objects means, it can allow us to store same type of objects and different type of objects.
• Same type means, assuming that all objects are in the form of integer types.
• Different type means, assuming that all objects are in the form of integer, float, String, Student and Customer types also.
• Size will increase dynamically.
• HashMap is non synchronized.
• Order is no guarantee.

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Program         :       Example on HashMap class

Program name  :       HMDemo1.java

Output            :         

      {1=Nireekshan, 2=Sravan, 3=Hari, 9=Mohan, 10=Mouli}

     

import java.util.HashMap;

class HMDemo1

{

       public static void main(String args[])

       {

             HashMap hashMap = new HashMap();

              

             hashMap.put(1, "Nireekshan");

             hashMap.put(2, "Sravan");
             hashMap.put(10, "Mouli");

             hashMap.put(9, "Mohan");

             hashMap.put(3, "Hari");
             

             System.out.println(hashMap);

       }

}

Compile       :         javac HMDemo1.java

Run             :         java HMDemo1

Output        :         

     {1=Nireekshan, 2=Sravan, 3=Hari, 9=Mohan, 10=Mouli}

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Thanks for your time.

Nireekshan