import java.util.*; class Main { // This function prints the first repeated // character in str[] static char firstRepeating(char str[]) { // Creates an empty hashset HashSet<Character> h = new HashSet<>(); // Traverse the input array from left to right for (int i=0; i<=str.length-1; i++) { char c = str[i]; // If element is already in hash set, update x // and then break if (h.contains(c)) return c; else // Else add element to hash set h.add(c); } return '\0'; } // Driver method to test above method public static void main (String[] args) { String str = "geeksforgeeks"; char[] arr = str.toCharArray(); System.out.println(firstRepeating(arr)); } }