Object-Oriented Programming: Exceptions
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Questions and Answers

What is an exception in programming?

  • A syntax error that prevents code compilation
  • An indication of a problem arising during program execution (correct)
  • A type of variable error that occurs at compile time
  • A logical error that can be found through debugging

    • What kind of error occurs when a file cannot be opened for writing?

  • Runtime error
  • Design error
  • Data error
  • Compile-time error (correct)

    • What will happen if a user inputs a non-integer value into the TestException program?

  • The program will ignore the input and assign a default value
  • The program will throw a runtime error (correct)
  • The program will throw a compile-time error
  • The program will exit gracefully without any errors

    • In the case of dividing by zero, which type of error is expected?

    <p>Runtime error</p> Signup and view all the answers

    What is typically the result of catching an exception in a program?

    <p>Control is transferred back to a designated block of code</p> Signup and view all the answers

    Which of the following indicates a situation where an exception might not be caught?

    <p>When no exception handling code is implemented</p> Signup and view all the answers

    What is the purpose of rethrowing an exception?

    <p>To pass the exception to outer levels for handling</p> Signup and view all the answers

    What type of error could arise from incorrect data inputs, such as strings instead of integers?

    <p>Data error</p> Signup and view all the answers

    Which statement about exceptions is incorrect?

    <p>All exceptions can be caught by a single try block.</p> Signup and view all the answers

    In the context of exception handling, what is tracing?

    <p>Systematically identifying the origin of an error</p> Signup and view all the answers

    What will happen if the denominator is set to zero in the Fraction constructor?

    <p>An ArithmeticException is thrown.</p> Signup and view all the answers

    In the context of exception handling, what is a throw point?

    <p>It is the initial point where the exception occurs.</p> Signup and view all the answers

    How does the catch block behave when an uncaught exception occurs?

    <p>It results in the program crashing with an error.</p> Signup and view all the answers

    What is the role of the 'throws' clause in a method header?

    <p>To specify the types of exceptions a method may throw.</p> Signup and view all the answers

    Which statement about the try block is correct?

    <p>It encloses code that might throw an exception.</p> Signup and view all the answers

    What could be a reason for an exception to be thrown during the execution of a program?

    <p>The program runs out of memory.</p> Signup and view all the answers

    What can a catch block catch besides exceptions of the declared type?

    <p>Exceptions that are subclasses of the declared type.</p> Signup and view all the answers

    Which of the following would prevent the main logic of the program from executing?

    <p>An unhandled exception in the try block.</p> Signup and view all the answers

    Why is error handling important in programming?

    <p>To separate logic from error handling.</p> Signup and view all the answers

    What happens if an exception is thrown and there is no matching catch block?

    <p>The exception will propagate and terminate the program.</p> Signup and view all the answers

    What is the result of executing the finally block in Java?

    <p>It executes after the catch block or if there is no catch block.</p> Signup and view all the answers

    In what scenario would you typically rethrow an exception?

    <p>When partial handling has taken place and further processing is needed.</p> Signup and view all the answers

    Which exception handling method allows for passing an exception to the caller?

    <p>Throwing exceptions.</p> Signup and view all the answers

    What is the purpose of the printStackTrace() method in exception handling?

    <p>To provide a detailed trace of the exception's occurrence.</p> Signup and view all the answers

    Which option correctly describes the NullPointerException in the provided example?

    <p>It occurs when trying to access a method on a null reference.</p> Signup and view all the answers

    What aspect of exception handling contributes to creating robust programs?

    <p>Resolving exceptions so programs can continue or terminate properly.</p> Signup and view all the answers

    What happens if the code in a try block does not throw an exception in relation to the finally block?

    <p>The finally block executes regardless of exceptions.</p> Signup and view all the answers

    What is a key feature of using catch and handle with exceptions?

    <p>It allows for specific handling of different exception types.</p> Signup and view all the answers

    What would be a consequence of failing to handle exceptions properly in a program?

    <p>The program may terminate unexpectedly or behave unpredictably.</p> Signup and view all the answers

    What is the primary function of the catch block in exception handling?

    <p>To perform a specific task when a particular exception is thrown.</p> Signup and view all the answers

    What happens when a valid input is provided to the try block containing 'int n = scanner.nextInt();'?

    <p>Both 'Ok' and 'Done.' will be printed.</p> Signup and view all the answers

    Which of the following scenarios will cause the catch block to be executed?

    <p>Providing a string input like 'abc' to 'scanner.nextInt();'</p> Signup and view all the answers

    In the context of exception handling, what is the purpose of the finally block?

    <p>It is always executed regardless of an exception.</p> Signup and view all the answers

    If an ArithmeticException is thrown but not caught, what happens next?

    <p>The program is terminated immediately.</p> Signup and view all the answers

    What does 'control gets out of the method' imply when an exception is not caught?

    <p>No further statements in the method are executed.</p> Signup and view all the answers

    How does the presence of 'System.exit()' affect the execution of finally block?

    <p>The finally block may not execute if reached after 'System.exit()'.</p> Signup and view all the answers

    What is likely to happen if 'scanner.nextInt();' throws an exception and there is no catch block?

    <p>The exception will be printed to the console.</p> Signup and view all the answers

    If multiple catch blocks are present, how does the Java runtime determine which catch block to execute?

    <p>It executes the first catch block that matches the type of the thrown exception.</p> Signup and view all the answers

    What behavior is expected if the statement 'int n = scanner.nextInt();' is inside a try block, but the scanner is not properly initialized?

    <p>The catch block will execute due to a NullPointerException.</p> Signup and view all the answers

    Study Notes

    Object-Oriented Programming: Exceptions

    • Exceptions: An indication of a problem during program execution
    • Types of Exceptions:
      • Design errors
      • Programming errors
      • Data errors
      • System errors

    Exception Handling

    • Purpose: Separating the normal program logic from error handling
    • Structure: The try block contains the code that might cause an exception. The catch block contains the code that handles the exception if one occurs

    Throwing Exceptions

    • Mechanism: An exception object is created and thrown, containing information about the error
    • throws Clause: Allows methods to declare what types of exceptions they might throw. This is done in the method's header.
    • Location: Exceptions can be thrown within the method body.

    Rethrowing Exceptions

    • Conditions: A catch block might rethrow an exception if it cannot fully handle it, or needs to pass it to a higher level in the program.
    • Example Use: Rethrowing is useful to pass the responsibility of dealing with an exception to a different part of the program.

    Exception Hierarchy

    • Hierarchy: Exceptions are organized by a hierarchy, like a tree, with Throwable at the top. This helps programs determine what type of exception occurred.
    • Examples of Exception types: Many types of exception are listed in the exception hierarchy. Some are ArithmeticException, NullPointerException, FileNotFoundException and IOException
    • printStackTrace() method: To trace the call stack (method calls leading up to the exception) to identify where in the program the error happened.

    finally Block

    • Purpose: To ensure that cleanup code executes regardless of whether an exception occurred or not.
    • Placement: It is placed after the last catch block (if any) in a try...catch statement.
    • Use Cases: Often used for closing resources like files, releasing locks, or performing other essential cleanup actions (e.g. closing a file, or releasing a lock)
    • Execution Guarantees: The finally block will always execute unless the program terminates unexpectedly. For example, the only scenario in which it will likely be skipped is if the application shut down using System.exit().

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    Java Exceptions PDF

    Description

    Test your knowledge on exceptions in object-oriented programming, focusing on types, handling, throwing, and rethrowing exceptions. This quiz covers essential concepts to effectively manage errors in your code.

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