Throw keyword in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to throw an exception when the number is negative.

Java

if (number < 0) {
    [1] new IllegalArgumentException("Negative number not allowed");
}

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

Atry

Bthrows

Ccatch

Dthrow

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'throws' instead of 'throw' to throw an exception.

Trying to use 'catch' or 'try' to throw an exception.

The throw keyword is used to actually throw an exception object in Java.

2fill in blank

medium

Complete the method to throw a NullPointerException when input is null.

Java

public void checkInput(String input) {
    if (input == null) {
        [1] new NullPointerException("Input cannot be null");
    }
}

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

Athrows

Bthrow

Ctry

Dcatch

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'throws' inside the method body instead of 'throw'.

Trying to catch the exception instead of throwing it.

The throw keyword is used to throw an exception instance inside the method.

3fill in blank

hard

Fix the error in throwing a checked exception inside the method.

Java

public void readFile(String path) [1] {
    if (path == null) {
        throw new IOException("File path is null");
    }
}

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

Athrows IOException

Bthrow IOException

Cthrows IOException()

Dthrow IOException()

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'throw' in method signature instead of 'throws'.

Adding parentheses after IOException in the signature.

Checked exceptions like IOException must be declared in the method signature using throws.

4fill in blank

hard

Fill both blanks to throw an ArithmeticException when dividing by zero.

Java

public int divide(int a, int b) [1] {
    if (b == 0) {
        [2] new ArithmeticException("Cannot divide by zero");
    }
    return a / b;
}

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

Athrows ArithmeticException

Bthrow

Cthrows IOException

Dthrow new

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'throw' in the method signature instead of 'throws'.

Using 'throw new' as a single option instead of splitting keywords.

The method declares throws ArithmeticException and inside the method, use throw to throw the exception.

5fill in blank

hard

Fill all three blanks to throw a custom exception when age is invalid.

Java

public void setAge(int age) [1] {
    if (age < 0 || age > 150) {
        [2] new [3]("Invalid age: " + age);
    }
}

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

Athrows InvalidAgeException

Bthrow

CInvalidAgeException

Dthrows Exception

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'throws Exception' instead of the specific custom exception.

Not using 'throw' keyword inside the method body.

The method declares it throws InvalidAgeException, inside it uses throw to throw a new InvalidAgeException object.