Java code to find duplicate Characters in a String

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

public class FindDuplicateChar {

    public static void countDuplicate(String str){

        /*Create a Map to store each Character with their count */

        Map<Character, Integer> charMap = new HashMap<Character, Integer>();

        /* Get Character array from String */

        char[] charArray = str.toCharArray();

        /*Iterate over Char Array and populate map*/

        for(Character ch:charArray){

            if(charMap.containsKey(ch)){

                charMap.put(ch, charMap.get(ch)+1);

            } else {

                charMap.put(ch, 1);

            }

        }

        /* Print Character with their count */

        for (Map.Entry entry:charMap.entrySet()) {

            System.out.println(entry.getKey()+" = "+entry.getValue());

        }

    }

    public static void main(String a[]){

        FindDuplicateChar obj = new FindDuplicateChar();

        String text = "ABCDABCDEFGHIJKLABCD";

        System.out.println("Text -"+text);

        FindDuplicateChar.countDuplicate(text);

    }

}