How to find duplicates in array in java using HASHMAP.?

Ravi Ranjan     2022-10-06 17:43:33    

How to find duplicates in array in java using HASHMAP.?

Java HashMap class implements the Map interface which allows us to store key and value pair, where keys should be unique.

Notes: 

• Java HashMap contains values based on the key.
• Java HashMap contains only unique keys.
• Java HashMap may have one null key and multiple null values.
• Java HashMap is non synchronized.
• Java HashMap maintains no order.
  
  
  import java.util.HashMap;

  import java.util.HashSet;

  import java.util.Map;

  import java.util.Map.Entry;

  import java.util.Set;

  
  
  

  public class DuplicateValue

  {

      public static void main(String[] args) {

        String [] inputArray = {"a","b","c","d","a"};

  
  

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

        for(String name: inputArray)  {

            Integer count=hm.get(name);

            if(count==null){

                hm.put(name,1);

            }else {

                  hm.put(name, ++count);

              }

        }

  
  

     

     

         Set<Entry<String, Integer>> entrySet = hm.entrySet();

         for (Entry<String, Integer> entry : entrySet) {

             if (entry.getValue() > 1) {

                 System.out.println("Duplicate element from array : " + entry.getKey());

                  } }

  
  

      }

  
  
  

  }