// Custom exception class class NegativeNumberException extends Exception { public NegativeNumberException(String message) { super(message); } } // Class using the custom exception public class CustomExceptionExample { public static void main(String[] args) { try { int result = calculateSquare(5); System.out.println("Square: " + result); result = calculateSquare(-3); // This will throw NegativeNumberException System.out.println("Square: " + result); // This line won't be executed } catch (NegativeNumberException e) { System.out.println("Error: " + e.getMessage()); } } // Method that may throw the custom exception private static int calculateSquare(int number) throws NegativeNumberException { if (number < 0) { // Throw the custom exception if the number is negative throw new NegativeNumberException("Negative numbers are not allowed."); } return number * number; } }