First recurring character

import java.util.Set;

import java.util.HashSet;

import java.util.Arrays;

class Main {

public static void main(String[] args) {

int[] array = {2, 5, 1, 2, 3, 5, 1, 2, 4};

System.out.println("First recurring character from array " + Arrays.toString(array) + " is " + firstRecurringCharacter(array));

array = new int[] {2, 1, 1, 2, 3, 5, 1, 2, 4};

System.out.println("First recurring character from array " + Arrays.toString(array) + " is " + firstRecurringCharacter(array));

array = new int[] {2, 3, 4, 5};

System.out.println("First recurring character from array " + Arrays.toString(array) + " is " + firstRecurringCharacter(array));

}

public static Integer firstRecurringCharacter(int[] characters) {

Set<Integer> charactersFound = new HashSet<>();

for (int character : characters) {

if (charactersFound.contains(character)) {

return character;

} else {

charactersFound.add(character);

}

}

return null;

}

}