import java.util.Hashtable;

import java.util.Map.Entry;

class DuplicateCharacter

{

public static void main(String[] args)

{

String str = "This is a string";

String[] arr = str.split(" ");

StringBuilder sb = new StringBuilder();

for(int i = 0 ; i < arr.length ; i++){

sb.append(arr[i]);

}

String send = sb.toString();

printDuplicate(send);

}

public static void printDuplicate(String str){

System.out.println(str);

str = str.toLowerCase();

Hashtable<Character,Integer> hm = new Hashtable<Character,Integer>();

for(int i = 0 ; i < str.length(); i++){

//System.out.println(str.charAt(i));

if(hm.isEmpty()){

hm.put(str.charAt(i),1);

}else if(hm.containsKey(str.charAt(i))){

hm.put(str.charAt(i),hm.get(str.charAt(i)) + 1);

}else{

hm.put(str.charAt(i),1);

}

}

for(Entry<Character,Integer> entry : hm.entrySet()){

if(entry.getValue() > 1){

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

}

}

}

}