Java Proficiency: hashmap example in java

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Sunday, 14 June 2015

How to get size of HashMap

import java.util.HashMap;
import java.util.Map;

public class HashMapKeyCount {

    public static void main(String[] args) {

        Map<Integer,String> hm = new HashMap<Integer,String>();

        /*
        * Associates the specified value with the specified key in
           this map (optional operation). If the map previously
           contained a mapping for the key, the old value is
           replaced by the specified value
        */
            hm.put(1,"ankush");
            hm.put(2, "amit");
            hm.put(3,"shivam");
            hm.put(4,"ankit");
            hm.put(5, "yogesh");

            //Returns the number of key-value mappings in this map

            System.out.println("HashMap size = "+hm.size());


        }

}

Output:

HashMap size = 5