Checked vs unchecked exceptions in Java - Interactive Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to declare a method that throws a checked exception.

Java

public void readFile() throws [1] {
    // method body
}

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ARuntimeException

BNullPointerException

CError

DIOException

Attempts:

3 left

💡 Hint

Common Mistakes

Using unchecked exceptions like RuntimeException in throws clause.

The IOException is a checked exception, so it must be declared with throws.

2fill in blank

medium

Complete the code to catch an unchecked exception.

Java

try {
    int result = 10 / 0;
} catch ([1] e) {
    System.out.println("Cannot divide by zero");
}

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AFileNotFoundException

BIOException

CArithmeticException

DSQLException

Attempts:

3 left

💡 Hint

Common Mistakes

Catching checked exceptions unrelated to arithmetic operations.

ArithmeticException is an unchecked exception thrown when dividing by zero.

3fill in blank

hard

Fix the error in the code by choosing the correct exception type to declare.

Java

public void connect() throws [1] {
    // code that may throw exception
}

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ASQLException

BNullPointerException

CRuntimeException

DIllegalArgumentException

Attempts:

3 left

💡 Hint

Common Mistakes

Declaring unchecked exceptions like RuntimeException in throws clause.

SQLException is a checked exception and must be declared in the method signature.

4fill in blank

hard

Fill both blanks to complete the code that handles a checked exception properly.

Java

try {
    FileReader file = new FileReader("file.txt");
} catch ([1] e) {
    System.out.println("File not found: " + e.getMessage());
} finally {
    [2]
}

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AFileNotFoundException

BIOException

Cfile.close()

DSystem.exit(0)

Attempts:

3 left

💡 Hint

Common Mistakes

Catching wrong exception types or forgetting to close the file.

The FileNotFoundException is a checked exception that must be caught. The file.close() in finally ensures the file resource is closed.

5fill in blank

hard

Fill all three blanks to create a method that throws a checked exception and handles an unchecked exception.

Java

public void process() throws [1] {
    try {
        int[] arr = new int[5];
        int x = arr[10];
    } catch ([2] e) {
        System.out.println("Index error: " + e.getMessage());
    }
    throw new [3]("File error");
}

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AIOException

BArrayIndexOutOfBoundsException

CFileNotFoundException

DRuntimeException

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing checked and unchecked exceptions incorrectly.

The method declares it throws FileNotFoundException (a checked exception). It catches ArrayIndexOutOfBoundsException (an unchecked exception) inside the try-catch block. Then it throws a new FileNotFoundException.