Find the First Repeated Word in a String in Java

To find the first repeated word in a string in Java, the code is as follows −

Example

 Live Demo

import java.util.*;
public class Demo{
   static char repeat_first(char my_str[]){
      HashSet<Character> my_hash = new HashSet<>();
      for (int i=0; i<=my_str.length-1; i++){
         char c = my_str[i];
         if (my_hash.contains(c))
         return c;
         else
         my_hash.add(c);
      }
      return '\0';
   }
   public static void main (String[] args){
      String my_str = "thisisasampleonlysample";
      char[] my_arr = my_str.toCharArray();
      System.out.println("The first repeating character in the string is :");
      System.out.println(repeat_first(my_arr));
   }
}

Output

The first repeating character in the string is :
I

A class named Demo contains a function named ‘repeat_first’, that takes a character string as a parameter. It creates a new hash set and iterates over the string and checks if the character in the string is equal to a specific character.

If yes, then the character is returned, otherwise, the character is added to the hash set. This way, the second time a word is found, it is added to the hash set, and this becomes the first word, that was in the string more than once. In the main function, the string is defined and a character array is defined. The function ‘repeat_first’ is called on this character array. The relevant array is displayed on the console.