Write A Program to Print Duplicate Character & Count-In Java?

Write A Program to Print Duplicate Character & Count-In Java?

package com.java.collection.hashset;
import java.util.HashMap;
import java.util.Map;
import java.util.Set;
public class Details 
{
   public void countDupChars(String str)
   {	 
      //Create a HashMap 
      Map<Character, Integer> map = new HashMap<Character, Integer>(); 
      //Convert the String to char array
      char[] chars = str.toCharArray();
      /* logic: char are inserted as keys and their count
       * as values. If map contains the char already then
       * increase the value by 1
       */
      for(Character ch:chars)
      {
         if(map.containsKey(ch))
         {
            map.put(ch, map.get(ch)+1);
         }
         else
         {
            map.put(ch, 1);
         }
      }
      //Obtaining set of keys
      Set<Character> keys = map.keySet();
      /* Display count of chars if it is
       * greater than 1. All duplicate chars would be 
       * having value greater than 1.
       */
      for(Character ch:keys)
      {
         if(map.get(ch) > 1)
         {
            System.out.println("Char "+ch+" "+map.get(ch));
         }
      }
   }
   public static void main(String a[]){
      Details obj = new Details();
      System.out.println("SoftwareTestingBlog");
      System.out.println("-------------------------");
      obj.countDupChars("mm");

   }
}

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Reference: Article