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Print all duplicate characters from a string

 In this question, we have to print duplicate characters i.e. the characters which come more than once in the given string.

ex:-

  • java (in "java",  'a' is the only duplicate character as it comes more than once, other than that 'j' and 'v' comes only one time in the given string ).
  • python ( in "python" all the characters come only on time so there is no duplicate character in the given string "python").

Java

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 import java.util.Scanner;
 public class PrintDuplicateCharacters {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String duplicate_str = "";
        String str = sc.next();
        for (int i = 0; i < str.length(); i++) {
            char c = str.charAt(i);
            if ((str.indexOf(c)!= str.lastIndexOf(c)) && !duplicate_str.contains(c + ""))
            {
                duplicate_str += c;
            }

        }
        System.out.println(duplicate_str);
    }
 }

Java ( using HashMap )

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import java.util.*;
public class PrintDuplicate{
     public static void main(String []args){
        String s = "codecheistc" ;
        Map<Character,Integer> hm = new HashMap();
        for(int i=0; i<s.length(); i++){
            char ch = s.charAt(i);
            if(hm.containsKey(ch))
                hm.put(ch, hm.get(ch)+1);
            else
                hm.put(ch, 1);
        }
        hm.forEach( (K, V) -> {
            if(V>1)
                System.out.print(K+" ");
        });
     }
 }

Python

input_str = input("Enter String:")
duplicate_str = ""
for i in range(0,len(input_str)-1):
    if input_str[i] in input_str[i+1:] and input_str[i] not in duplicate_str:
        duplicate_str += input_str[i]
print(duplicate_str)