AP Computer Science Exam Question - Try-Catch Blocks

In a Java program, consider the following code segment:

public class TryCatchExample {

    public static void main(String[] args) {
        try {
            int[] numbers = {1, 2, 3};
            System.out.println(numbers[4]);
        } catch (ArrayIndexOutOfBoundsException e) {
            System.out.println("Error: Array Index Out Of Bounds!");
        }
    }
}

1. What is the purpose of the try-catch block in the code segment provided?

a) It handles a compile-time error. b) It catches a runtime exception. c) It checks if the array numbers is empty. d) It ensures that the element at index 4 of the array numbers is accessed safely.

Answer:

Option b) It catches a runtime exception.

Explanation:

• In the given code segment, a try-catch block is used to catch a specific runtime exception, which is the ArrayIndexOutOfBoundsException.
• When the code System.out.println(numbers[4]); is executed, it tries to access an element at index 4 in the numbers array. However, since arrays are zero-indexed in Java, and the numbers array only has elements at indices 0, 1, and 2, accessing the element at index 4 will result in an ArrayIndexOutOfBoundsException.
• The try block is intended for the potentially problematic code that might throw an exception. If an exception occurs within the try block, the program flow is immediately transferred to the corresponding catch block.
• In this case, since accessing an element out of bounds of an array is a runtime exception, the catch block with the appropriate ArrayIndexOutOfBoundsException parameter is executed.
• The catch block then prints the error message "Error: Array Index Out Of Bounds!" to the console.

Thus, option b) accurately describes the purpose of the given try-catch block since it catches the specific runtime exception that might occur in the code segment.