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Sunday, 14 June 2015

How to get all keys of HashMap

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

public class HashMapGetAllKeys {



        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 a Set view of the keys contained in this map
             */
           
            Set<Integer> keys =hm.keySet();
           
            for (Integer key : keys) {
                System.out.println(" key ="+key);
            }
        }
   
}

Output:

  key =1

  key =2

  key =3

  key =4
 
  key =5

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