Why exception handling is required in Java - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to catch an exception when dividing by zero.

Java

try {
    int result = 10 / [1];
} catch (ArithmeticException e) {
    System.out.println("Cannot divide by zero.");
}

Drag options to blanks, or click blank then click option'

A10

B1

C2

D0

Attempts:

3 left

💡 Hint

Common Mistakes

Using a non-zero number which does not cause an exception.

Dividing by zero causes an ArithmeticException, so the blank must be 0 to trigger the exception.

2fill in blank

medium

Complete the code to handle a possible null pointer exception.

Java

String text = null;
try {
    int length = text.[1]();
} catch (NullPointerException e) {
    System.out.println("Text is null.");
}

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Alength()

BcharAt

Clength

DtoString

Attempts:

3 left

💡 Hint

Common Mistakes

Using length without parentheses which is invalid for String.

The method length() is called on a null string, which causes NullPointerException.

3fill in blank

hard

Fix the error in the code to properly catch exceptions.

Java

try {
    int[] arr = new int[3];
    int value = arr[5];
} catch ([1] e) {
    System.out.println("Index out of bounds.");
}

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AArithmeticException

BNullPointerException

CArrayIndexOutOfBoundsException

DIOException

Attempts:

3 left

💡 Hint

Common Mistakes

Catching the wrong exception type that does not match the error.

Accessing an invalid array index throws ArrayIndexOutOfBoundsException.

4fill in blank

hard

Fill both blanks to create a try-catch block that handles file reading exceptions.

Java

try {
    FileReader file = new FileReader("test.txt");
    BufferedReader reader = new BufferedReader(file);
    String line = reader.readLine();
} catch ([1] e) {
    System.out.println("File not found.");
} catch ([2] e) {
    System.out.println("IO error occurred.");
}

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AFileNotFoundException

BNullPointerException

CIOException

DArithmeticException

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the order of exceptions or using unrelated exceptions.

FileNotFoundException handles missing file errors, IOException handles other input/output errors.

5fill in blank

hard

Fill all three blanks to create a method that throws and catches a custom exception.

Java

class MyException extends Exception {}

public class Test {
    public static void check(int num) throws [1] {
        if (num < 0) {
            throw new [2]();
        }
    }

    public static void main(String[] args) {
        try {
            check(-1);
        } catch ([3] e) {
            System.out.println("Custom exception caught.");
        }
    }
}

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AMyException

DException

Attempts:

3 left

💡 Hint

Common Mistakes

Using Exception instead of the custom exception class.

The method declares throwing MyException, throws it when condition meets, and catches it in main.