Chapter 11 - Exceptions and Localization

Question 1

Supporting localization means you must immediately support specific languages. If false, why?

Answer 1

False. Localization support can be built early without implementing specific languages right away.

Question 2

An exception is an event that alters program flow. If false, why?

Answer 2

True

Question 3

All Java exceptions have “Exception” in their class name. If false, why?

Answer 3

False. Some exceptions, like Error and Throwable, do not include “Exception” in their name.

Question 4

A checked exception must be declared or handled where it is thrown. If false, why?

Answer 4

True

Question 5

Checked exceptions inherit Exception but not RuntimeException. If false, why?

Answer 5

True

Question 6

Checked exceptions include all classes that inherit Throwable. If false, why?

Answer 6

False. Only classes that extend Exception but not Error or RuntimeException are checked exceptions.

Question 7

The handle or declare rule applies to all exceptions. If false, why?

Answer 7

False. It only applies to checked exceptions, not unchecked exceptions like RuntimeException.

Question 8

The throw keyword declares that a method might throw an exception. If false, why?

Answer 8

False. throw is used to actually throw an exception, while throws declares it in a method signature.

Question 9

Checked exceptions require handling because they are usually anticipated. If false, why?

Answer 9

True

Question 10

A catch block that catches Exception can handle IOException. If false, why?

Answer 10

True

Question 11

A runtime exception is a subclass of RuntimeException and tends to be unexpected but not necessarily fatal.

Answer 11

True

Question 11

An unchecked exception does not need to be declared or handled by the application code where it is thrown.

Answer 11

True

Question 12

Errors indicate severe problems that a program should not attempt to recover from.

Answer 12

True

Question 13

Throwable is the parent class of all exceptions, including both checked and unchecked exceptions.

Answer 13

True

Question 14

The throw keyword is used to throw a new exception or rethrow an existing one inside a code block.

Answer 14

True

Question 15

The throws keyword is used at the end of a method declaration to indicate what exceptions a method can throw.

Answer 15

True

Question 16

An unchecked exception must be handled by the program.

Answer 16

No, handling is optional.)

Question 17

Errors are checked exceptions that must be declared or handled.

Answer 17

(Errors are not checked exceptions and should not be handled.)

Question 18

Throwable should always be caught directly in application code.

Answer 18

It is not recommended to catch Throwable directly.

Question 19

A checked exception is a subclass of RuntimeException.

Answer 19

Checked exceptions are subclasses of Exception but not of RuntimeException.

Question 20

The throw keyword is used at the method declaration to indicate possible exceptions.

Answer 20

No, that’s the throws keyword.

Question 21

A program is required to handle or declare all exceptions.

Answer 21

Only checked exceptions must be handled or declared.)

Question 22

Errors are typically recoverable in Java applications.

Answer 22

Errors represent serious issues that should not be recovered from.

Question 23

RuntimeException is a checked exception.

Answer 23

No, it is an unchecked exception.

Question 24

The throws keyword is used inside a method body to throw an exception.

Answer 24

(No, the throw keyword is used for that.)

Question 25

An exception cannot be stored in an object reference.

Answer 25

No, an exception is an object and can be stored in a reference.

Question 26

Any Java code can throw an exception, including both user-written and built-in Java code.

Answer 26

True

Question 27

An ArrayIndexOutOfBoundsException occurs at compile time when accessing an invalid array index.

Answer 27

(Correction: It occurs at runtime, not compile time.)

Question 28

The throw keyword is used in a method declaration to specify what exceptions a method can throw.

Answer 28

(Correction: The throws keyword is used for that, not throw.)

Question 29

The throw keyword is used inside a code block to throw an exception.

Answer 29

True

Question 30

Java automatically throws an exception if a method contains the word throw anywhere in its body.

Answer 30

(Correction: The throw statement must be explicitly executed.)

Question 31

A method must always specify throws when using throw inside it.

Answer 31

(Correction: Only checked exceptions require throws, not unchecked exceptions.)

Question 32

An exception is an object in Java, meaning it can be stored in a variable.

Answer 32

True.

Question 33

You can throw an exception without using the new keyword.

Answer 33

(Correction: The exception must be instantiated with new.)

Question 34

throw new RuntimeException("Error message"); is a valid statement in Java.

Answer 34

True

Question 35

The compiler ignores unreachable code errors caused by exceptions.

Answer 35

(Correction: The compiler reports an error for unreachable code.)

Question 36

throw RuntimeException(); is valid Java syntax.

Answer 36

(Correction: It must be throw new RuntimeException();.)

Question 37

A method can throw an exception that was passed into it as a parameter.

Answer 37

True

Question 38

A method marked with throws must handle the exception inside the method.

Answer 38

(Correction: The method does not need to handle it; it delegates handling to the caller.)

Question 39

If a try block throws an exception, all lines after it in the try block will still execute.

Answer 39

(Correction: Execution jumps to the catch block, skipping remaining try statements.)

Question 40

Java allows multiple throw statements on consecutive lines in a try block.

Answer 40

(Correction: The second throw statement would be unreachable if the first always executes.)

Question 41

Java enforces a default message for all exception objects if none is provided.

Answer 41

(Correction: Some exceptions may have null messages if none is set.)

Question 42

A throws clause is required for all exceptions in Java.

Answer 42

(Correction: Only checked exceptions require throws; runtime exceptions do not.)

Question 43

A try block is mandatory when using the throw keyword.

Answer 43

(Correction: A throw statement can exist without a try block, but it may cause an uncaught exception.)

Question 44

What is AutoCloseable?

Answer 44

✔ AutoCloseable is an interface for objects that hold resources (e.g., files, sockets). ✔ Ensures resources are automatically closed when used in a try-with-resources block. ✔ Introduced in Java 7.

Question 45

How does AutoCloseable work?

Answer 45

✔ Declaring an AutoCloseable object in a try-with-resources block ensures its close() method is called automatically.

Question 46

Why use AutoCloseable?

Answer 46

✔ Prevents resource leaks (e.g., unclosed files, sockets, database connections). ✔ Avoids manual cleanup using finally blocks. ✔ Improves code readability and maintainability.

Question 47

What is the difference between AutoCloseable and Closeable?

Answer 47

✔ Closeable (from java.io) is specific to I/O resources. ✔ AutoCloseable is more general, allowing any resource to be closed. ✔ AutoCloseable.close() can throw any exception, while Closeable.close() only throws IOException.

Question 48

When should you NOT use try-with-resources?

Answer 48

✔ When working with non-I/O-based resources (e.g., Stream operations). ✔ If the resource does not actually require cleanup.

Question 49

Why is close() called before catch?

Answer 49

✔ In a try-with-resources block, resources declared in the header are closed before handling exceptions. ✔ This ensures proper resource cleanup before exception handling begins.

Question 50

How does Java ensure close() runs first?

Answer 50

✔ The Java compiler automatically inserts a finally block to close the resource before the catch block runs. ✅ This guarantees proper cleanup, preventing resource leaks.

Question 51

What happens if close() itself throws an exception?

Answer 51

✔ If close() throws an exception, it is suppressed and attached to the original exception. ✔ You can retrieve suppressed exceptions using Throwable.getSuppressed().

Question 52

In what order are resources closed in try-with-resources?

Answer 52

✔ Resources are closed in the reverse order of their creation.

Question 53

Are resources always closed, even if an exception occurs?

Answer 53

✔ Yes! Resources are always closed, even if an exception is thrown.

Question 54

When are catch and finally blocks executed regarding the close?

Answer 54

✔ catch and finally blocks execute after resources are closed. try (MyResource res = new MyResource()) { throw new RuntimeException("Error!"); } catch (Exception e) { System.out.println("Caught: " + e.getMessage()); } ✅ First res.close(), then catch executes.

Question 55

What happens if an exception is thrown in catch or finally?

Answer 55

✔ It does not prevent resources from being closed.

Question 56

Do resources close before finally executes?

Answer 56

✔ Yes, resources close before finally executes.

Question 57

What must be true about a checked exception declared inside a catch block?

Answer 57

The associated try block must be capable of throwing that exception or a subclass; otherwise, the code is unreachable and does not compile.

Question 58

Does the rule about checked exceptions in a catch block apply to unchecked exceptions?

Answer 58

No, the rule applies only to checked exceptions, not to unchecked exceptions or exceptions declared in a method signature.

Question 59

What is the rule for overriding methods with checked exceptions?

Answer 59

An overridden method may not declare any new or broader checked exceptions than the method it inherits.

Question 60

What are the three ways to print an exception in Java?

Answer 60

1. Print the exception object (System.out.println(e)). 2. Print just the message (System.out.println(e.getMessage())). 3. Print the stack trace (e.printStackTrace()).

Question 61

Why is the stack trace the most helpful way to print an exception?

Answer 61

It shows the hierarchy of method calls that led to the exception, making it easier to debug the issue.

Question 62

What are the three main groups of exceptions in Java?

Answer 62

1. RuntimeException (unchecked exceptions) 2. Checked exceptions 3. Error

Question 63

What is a RuntimeException in Java?

Answer 63

It is an unchecked exception that does not need to be declared or handled explicitly.

Question 64

When is an ArithmeticException thrown?

Answer 64

When code attempts to divide by zero.

Question 65

When is an ArrayIndexOutOfBoundsException thrown?

Answer 65

When code tries to access an array using an illegal index.

Question 66

When is a NullPointerException thrown?

Answer 66

When a null reference is used where an object is required.

Question 67

When is an IllegalArgumentException typically thrown?

Answer 67

When a method is passed an illegal or inappropriate argument.

Question 68

What is NumberFormatException, and what causes it?

Answer 68

It is a subclass of IllegalArgumentException, thrown when trying to convert a String to a numeric type but the format is incorrect.