Multiple catch blocks in Java - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to catch an ArithmeticException.

Java

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

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

ANullPointerException

BIOException

CArithmeticException

DArrayIndexOutOfBoundsException

Attempts:

3 left

💡 Hint

Common Mistakes

Using IOException instead of ArithmeticException.

Catching NullPointerException which is unrelated here.

The code tries to divide by zero, which throws an ArithmeticException. The catch block must specify ArithmeticException to handle it.

2fill in blank

medium

Complete the code to catch a NullPointerException.

Java

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

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

ANullPointerException

BIOException

CArithmeticException

DNumberFormatException

Attempts:

3 left

💡 Hint

Common Mistakes

Catching IOException which is unrelated.

Using ArithmeticException which is for math errors.

Calling length() on a null string throws a NullPointerException. The catch block must handle this exception.

3fill in blank

hard

Fix the error in the catch block to handle NumberFormatException.

Java

try {
    int num = Integer.parseInt("abc");
} catch ([1] e) {
    System.out.println("Invalid number format.");
}

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

AIOException

BArithmeticException

CNullPointerException

DNumberFormatException

Attempts:

3 left

💡 Hint

Common Mistakes

Catching IOException which is unrelated here.

Using ArithmeticException which is for math errors.

Parsing "abc" as an integer throws a NumberFormatException. The catch block must specify this exception to handle it.

4fill in blank

hard

Fill both blanks to catch ArithmeticException and NullPointerException separately.

Java

try {
    int result = 10 / 0;
    String text = null;
    int length = text.length();
} catch ([1] e) {
    System.out.println("Arithmetic error occurred.");
} catch ([2] e) {
    System.out.println("Null pointer error occurred.");
}

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

AArithmeticException

BIOException

CNullPointerException

DNumberFormatException

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping the exception types in the catch blocks.

Using unrelated exceptions like IOException.

The first catch block handles ArithmeticException from dividing by zero. The second catch block handles NullPointerException from calling a method on null.

5fill in blank

hard

Fill all three blanks to catch NumberFormatException, ArithmeticException, and NullPointerException in separate catch blocks.

Java

try {
    int num = Integer.parseInt("abc");
    int result = 10 / 0;
    String text = null;
    int length = text.length();
} catch ([1] e) {
    System.out.println("Number format error.");
} catch ([2] e) {
    System.out.println("Arithmetic error.");
} catch ([3] e) {
    System.out.println("Null pointer error.");
}

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

AIOException

BArithmeticException

CNullPointerException

DNumberFormatException

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the order of exceptions in catch blocks.

Using IOException which is unrelated.

The first catch block handles NumberFormatException from parsing "abc". The second handles ArithmeticException from dividing by zero. The third handles NullPointerException from calling a method on null.

Practice

1.

What is the main purpose of using multiple catch blocks in Java?

easy

A. To handle different types of exceptions separately

B. To run all catch blocks regardless of exception type

C. To improve program speed by skipping exceptions

D. To avoid using try blocks

Solution

1. Step 1: Understand exception handling

   Multiple catch blocks allow handling different exceptions in different ways.

2. Step 2: Identify the purpose

   Each catch block targets a specific exception type, so only the matching one runs.

3. Final Answer:

   To handle different types of exceptions separately -> Option A

4. Quick Check:

   Multiple catch blocks = handle exceptions separately [OK]

Hint: Multiple catch blocks handle different exceptions separately [OK]

Common Mistakes:

• Thinking all catch blocks run for one exception
• Believing catch blocks improve speed
• Confusing catch blocks with try blocks

2.

Which of the following is the correct syntax for multiple catch blocks in Java?

try {
    // code
} catch (IOException e) {
    // handle IO
} catch (Exception e) {
    // handle general
}

easy

A. try { } catch (Exception e) { } catch (IOException e) { }

B. try { } catch (IOException e) { } catch (Exception e) { }

C. try { } catch IOException e { } catch Exception e { }

D. try { } catch (Exception e) catch (IOException e) { }

Solution

1. Step 1: Check catch block order

   Specific exceptions like IOException must come before general ones like Exception.

2. Step 2: Verify syntax correctness

   Each catch block must have parentheses around exception type and variable.

3. Final Answer:

   try { } catch (IOException e) { } catch (Exception e) { } -> Option B

4. Quick Check:

   Specific before general, correct syntax [OK]

Hint: Put specific exceptions before general ones in catch blocks [OK]

Common Mistakes:

• Placing general exception before specific
• Missing parentheses in catch
• Combining catch blocks without braces

3.

What will be the output of the following code?

try {
    int[] arr = new int[2];
    System.out.println(arr[5]);
} catch (ArrayIndexOutOfBoundsException e) {
    System.out.println("Index error");
} catch (Exception e) {
    System.out.println("General error");
}

medium

A. No output

B. General error

C. ArrayIndexOutOfBoundsException

D. Index error

Solution

1. Step 1: Identify exception thrown

   Accessing arr[5] causes ArrayIndexOutOfBoundsException.

2. Step 2: Match catch block

   The first catch matches ArrayIndexOutOfBoundsException and prints "Index error".

3. Final Answer:

   Index error -> Option D

4. Quick Check:

   ArrayIndexOutOfBoundsException caught by first catch [OK]

Hint: First matching catch block runs for thrown exception [OK]

Common Mistakes:

• Thinking general catch runs first
• Expecting exception message printed
• Assuming no output on exception

4.

Find the error in this code snippet:

try {
    int a = 5 / 0;
} catch (Exception e) {
    System.out.println("Error");
} catch (ArithmeticException e) {
    System.out.println("Math error");
}

medium

A. Try block missing braces

B. Exception catch block should be removed

C. ArithmeticException catch block should come before Exception catch block

D. No error, code is correct

Solution

1. Step 1: Check catch block order

   More specific exceptions must come before general ones.

2. Step 2: Identify error

   ArithmeticException is a subclass of Exception, so its catch must be first.

3. Final Answer:

   ArithmeticException catch block should come before Exception catch block -> Option C

4. Quick Check:

   Specific before general catch order [OK]

Hint: Place specific exceptions before general ones in catch blocks [OK]

Common Mistakes:

• Putting general catch before specific
• Ignoring catch block order rules
• Assuming no compile error

5.

Consider this code:

try {
    String s = null;
    System.out.println(s.length());
} catch (NullPointerException e) {
    System.out.println("Null pointer caught");
} catch (RuntimeException e) {
    System.out.println("Runtime exception caught");
} catch (Exception e) {
    System.out.println("General exception caught");
}

What will be printed and why is the catch order important here?

hard

A. "Null pointer caught" because NullPointerException is caught first

B. "Runtime exception caught" because RuntimeException is more general

C. "General exception caught" because Exception is the base class

D. Compilation error due to catch order

Solution

1. Step 1: Identify exception thrown

   Calling length() on null throws NullPointerException.

2. Step 2: Check catch order

   NullPointerException is caught by the first catch block, which is specific and placed before general exceptions.

3. Step 3: Understand importance of order

   If general exceptions came first, specific ones would be unreachable causing compile error.

4. Final Answer:

   "Null pointer caught" because NullPointerException is caught first -> Option A

5. Quick Check:

   Specific exceptions first, correct catch order [OK]

Hint: Catch specific exceptions before general ones to avoid errors [OK]

Common Mistakes:

• Assuming general catch runs first
• Ignoring NullPointerException specifics
• Not knowing catch block order matters