Chapter 11 - Exceptions and Localization Flashcards
Supporting localization means you must immediately support specific languages. If false, why?
False. Localization support can be built early without implementing specific languages right away.
An exception is an event that alters program flow. If false, why?
True
All Java exceptions have “Exception” in their class name. If false, why?
False. Some exceptions, like Error and Throwable, do not include “Exception” in their name.
A checked exception must be declared or handled where it is thrown. If false, why?
True
Checked exceptions inherit Exception but not RuntimeException. If false, why?
True
Checked exceptions include all classes that inherit Throwable. If false, why?
False. Only classes that extend Exception but not Error or RuntimeException are checked exceptions.
The handle or declare rule applies to all exceptions. If false, why?
False. It only applies to checked exceptions, not unchecked exceptions like RuntimeException.
The throw keyword declares that a method might throw an exception. If false, why?
False. throw is used to actually throw an exception, while throws declares it in a method signature.
Checked exceptions require handling because they are usually anticipated. If false, why?
True
A catch block that catches Exception can handle IOException. If false, why?
True
A runtime exception is a subclass of RuntimeException and tends to be unexpected but not necessarily fatal.
True
An unchecked exception does not need to be declared or handled by the application code where it is thrown.
True
Errors indicate severe problems that a program should not attempt to recover from.
True
Throwable is the parent class of all exceptions, including both checked and unchecked exceptions.
True
The throw keyword is used to throw a new exception or rethrow an existing one inside a code block.
True
The throws keyword is used at the end of a method declaration to indicate what exceptions a method can throw.
True
An unchecked exception must be handled by the program.
No, handling is optional.)
Errors are checked exceptions that must be declared or handled.
(Errors are not checked exceptions and should not be handled.)
Throwable should always be caught directly in application code.
It is not recommended to catch Throwable directly.
A checked exception is a subclass of RuntimeException.
Checked exceptions are subclasses of Exception but not of RuntimeException.
The throw keyword is used at the method declaration to indicate possible exceptions.
No, that’s the throws keyword.
A program is required to handle or declare all exceptions.
Only checked exceptions must be handled or declared.)
Errors are typically recoverable in Java applications.
Errors represent serious issues that should not be recovered from.
RuntimeException is a checked exception.
No, it is an unchecked exception.
The throws keyword is used inside a method body to throw an exception.
(No, the throw keyword is used for that.)
An exception cannot be stored in an object reference.
No, an exception is an object and can be stored in a reference.
Any Java code can throw an exception, including both user-written and built-in Java code.
True
An ArrayIndexOutOfBoundsException occurs at compile time when accessing an invalid array index.
(Correction: It occurs at runtime, not compile time.)
The throw keyword is used in a method declaration to specify what exceptions a method can throw.
(Correction: The throws keyword is used for that, not throw.)
The throw keyword is used inside a code block to throw an exception.
True
Java automatically throws an exception if a method contains the word throw anywhere in its body.
(Correction: The throw statement must be explicitly executed.)
A method must always specify throws when using throw inside it.
(Correction: Only checked exceptions require throws, not unchecked exceptions.)
An exception is an object in Java, meaning it can be stored in a variable.
True.
You can throw an exception without using the new keyword.
(Correction: The exception must be instantiated with new.)
throw new RuntimeException(“Error message”); is a valid statement in Java.
True
The compiler ignores unreachable code errors caused by exceptions.
(Correction: The compiler reports an error for unreachable code.)
throw RuntimeException(); is valid Java syntax.
(Correction: It must be throw new RuntimeException();.)
A method can throw an exception that was passed into it as a parameter.
True
A method marked with throws must handle the exception inside the method.
(Correction: The method does not need to handle it; it delegates handling to the caller.)
If a try block throws an exception, all lines after it in the try block will still execute.
(Correction: Execution jumps to the catch block, skipping remaining try statements.)
Java allows multiple throw statements on consecutive lines in a try block.
(Correction: The second throw statement would be unreachable if the first always executes.)
Java enforces a default message for all exception objects if none is provided.
(Correction: Some exceptions may have null messages if none is set.)
A throws clause is required for all exceptions in Java.
(Correction: Only checked exceptions require throws; runtime exceptions do not.)
A try block is mandatory when using the throw keyword.
(Correction: A throw statement can exist without a try block, but it may cause an uncaught exception.)
What is AutoCloseable?
✔ 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.
How does AutoCloseable work?
✔ Declaring an AutoCloseable object in a try-with-resources block ensures its close() method is called automatically.
Why use AutoCloseable?
✔ Prevents resource leaks (e.g., unclosed files, sockets, database connections).
✔ Avoids manual cleanup using finally blocks.
✔ Improves code readability and maintainability.
What is the difference between AutoCloseable and Closeable?
✔ 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.
When should you NOT use try-with-resources?
✔ When working with non-I/O-based resources (e.g., Stream operations).
✔ If the resource does not actually require cleanup.
Why is close() called before catch?
✔ 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.
How does Java ensure close() runs first?
✔ The Java compiler automatically inserts a finally block to close the resource before the catch block runs.
✅ This guarantees proper cleanup, preventing resource leaks.
What happens if close() itself throws an exception?
✔ If close() throws an exception, it is suppressed and attached to the original exception.
✔ You can retrieve suppressed exceptions using Throwable.getSuppressed().
In what order are resources closed in try-with-resources?
✔ Resources are closed in the reverse order of their creation.
Are resources always closed, even if an exception occurs?
✔ Yes! Resources are always closed, even if an exception is thrown.
When are catch and finally blocks executed?
✔ 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.
What happens if an exception is thrown in catch or finally?
✔ It does not prevent resources from being closed.
Do resources close before finally executes?
✔ Yes, resources close before finally executes.
What must be true about a checked exception declared inside a catch block?
The associated try block must be capable of throwing that exception or a subclass; otherwise, the code is unreachable and does not compile.
Does the rule about checked exceptions in a catch block apply to unchecked exceptions?
No, the rule applies only to checked exceptions, not to unchecked exceptions or exceptions declared in a method signature.
What is the rule for overriding methods with checked exceptions?
An overridden method may not declare any new or broader checked exceptions than the method it inherits.
What are the three ways to print an exception in Java?
- Print the exception object (System.out.println(e)).
- Print just the message (System.out.println(e.getMessage())).
- Print the stack trace (e.printStackTrace()).
Why is the stack trace the most helpful way to print an exception?
It shows the hierarchy of method calls that led to the exception, making it easier to debug the issue.
What are the three main groups of exceptions in Java?
- RuntimeException (unchecked exceptions)
- Checked exceptions
- Error
What is a RuntimeException in Java?
It is an unchecked exception that does not need to be declared or handled explicitly.
When is an ArithmeticException thrown?
When code attempts to divide by zero.
When is an ArrayIndexOutOfBoundsException thrown?
When code tries to access an array using an illegal index.
When is a NullPointerException thrown?
When a null reference is used where an object is required.
When is an IllegalArgumentException typically thrown?
When a method is passed an illegal or inappropriate argument.
What is NumberFormatException, and what causes it?
It is a subclass of IllegalArgumentException, thrown when trying to convert a String to a numeric type but the format is incorrect.
