Find first non-repeating character Java

PROGRAM TO FIND FIRST NON-REPEATING CHARACTER IN A STRING IN ONE TRAVERSAL

class MAIN {

    static final int NO_OF_CHARS = 256;

    static char count[] = new char[NO_OF_CHARS];

  

    /* calculate count of characters 

       in the passed string */

    static void getCharCountArray(String str)

    {

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

            count[str.charAt(i)]++;

    }

  

    /* The method returns index of first non-repeating

       character in a string. If all characters are repeating 

       then returns -1 */

    static int firstNonRepeating(String str)

    {

        getCharCountArray(str);

        int index = -1, i;

  

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

            if (count[str.charAt(i)] == 1) {

                index = i;

                break;

            }

        }

  

        return index;

    }

  

    // Driver method

    public static void main(String[] args)

    {

        String str = "transgeek";

        int index = firstNonRepeating(str);

  

        System.out.println(

            index == -1

                ? "Either all characters are repeating or string "

                      + "is empty"

                : "First non-repeating character is "

                      + str.charAt(index));

    }

}




OUTPUT

First non-repeating character is t

CREDITS: https://www.geeksforgeeks.org/given-a-string-find-its-first-non-repeating-character/