Object-Oriented Programming: Inheritance and Constructors
24 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What type of error will occur in the program if an abstract method is declared as final in an abstract class?

  • Runtime Error
  • Compile Time Error (correct)
  • Logic Error
  • Syntax Error
  • What is the purpose of an abstract class in Java?

  • To provide a way to override methods
  • To provide a base class that cannot be instantiated (correct)
  • To provide a blueprint for objects that can be instantiated
  • To provide a way to implement multiple inheritance
  • What will happen if a subclass does not implement an abstract method inherited from its superclass?

  • The subclass will throw a logic error
  • The subclass will compile successfully
  • The subclass will not compile (correct)
  • The subclass will throw a runtime exception
  • What is the access modifier of the display method in the FourWheeler class?

    <p>Protected</p> Signup and view all the answers

    What is the relationship between the Car class and the FourWheeler class?

    <p>The Car class is a subclass of the FourWheeler class</p> Signup and view all the answers

    What is the output of the given program?

    <p>Class Audi Class Car Class FourWheeler</p> Signup and view all the answers

    What is the purpose of an abstract method in Java?

    <p>To declare a method that must be implemented by subclasses</p> Signup and view all the answers

    Why can't an abstract method be declared as final in an abstract class?

    <p>Because it would prevent subclasses from overriding the method</p> Signup and view all the answers

    What is the purpose of the super() call in the Audi class constructor?

    <p>To call the constructor of the <code>Car</code> class</p> Signup and view all the answers

    What is the consequence of not implementing an abstract method in a subclass?

    <p>The subclass will not compile</p> Signup and view all the answers

    What is the relationship between the Car and FourWheeler classes?

    <p>The <code>Car</code> class is a subclass of the <code>FourWheeler</code> class</p> Signup and view all the answers

    What happens when the Audi class constructor is called?

    <p>The <code>Audi</code> class constructor and its superclass constructors are called</p> Signup and view all the answers

    What is the purpose of the main method in the Driver class?

    <p>To start the execution of the program</p> Signup and view all the answers

    What is the inheritance hierarchy of the classes?

    <p>Audi -&gt; Car -&gt; FourWheeler</p> Signup and view all the answers

    What is the role of the System.out.println statements in the constructors?

    <p>To print the class names during constructor calls</p> Signup and view all the answers

    What is the relationship between the Audi and Driver classes?

    <p>The <code>Audi</code> class is used by the <code>Driver</code> class</p> Signup and view all the answers

    What type of exception will be thrown by the line Trial object = (Trial)new A();?

    <p>ClassCastException</p> Signup and view all the answers

    Why does the line Trial object = (Trial)new A(); throw an exception?

    <p>Because a parent object cannot be referred to by a child type reference</p> Signup and view all the answers

    What is the output of the given code?

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

    What is the purpose of the line Trial object = (Trial)new A();?

    <p>To upcast an object of class A to class Trial</p> Signup and view all the answers

    Why does the code not throw a Compile Time Error?

    <p>Because the code is syntactically correct</p> Signup and view all the answers

    What is the correct way to create an object of class Trial?

    <p>Trial object = new Trial();</p> Signup and view all the answers

    What is the relationship between class A and class Trial?

    <p>Class Trial is a subclass of class A</p> Signup and view all the answers

    What is the purpose of the extends keyword in the declaration of class Trial?

    <p>To extend a superclass</p> Signup and view all the answers

    Study Notes

    Inheritance

    • Inheritance allows a class to inherit properties and behavior from another class, creating a parent-child relationship.
    • A child class can extend a parent class, inheriting its properties and behavior.

    Constructors and Inheritance

    • When a child class is created, its constructor is called, followed by its parent's constructor.
    • The order of constructor calls is determined by the class hierarchy.
    • In the example, Audi class constructor calls Car class constructor, which in turn calls FourWheeler class constructor.

    Abstract Classes and Methods

    • An abstract class can have abstract methods, which must be implemented by its child classes.
    • An abstract method cannot be declared as final.
    • In the example, Shape class has an abstract method calcArea() which cannot be declared as final.

    Method Overriding

    • Method overriding occurs when a child class provides a different implementation for a method already defined in its parent class.
    • In the example, Trial class overrides test() method of A class.

    Runtime Errors

    • A runtime error occurs when a program encounters an error during execution, rather than at compile time.
    • In the example, Trial object = (Trial)new A(); produces a runtime error because a parent object cannot be referred by a child type reference.

    Compile Time Errors

    • A compile time error occurs when a program encounters an error during compilation, rather than at runtime.
    • In the example, the program produces a compile time error because the abstract method in the parent class has not found its implementation in the child class.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Java.pdf

    Description

    Learn about the concept of inheritance in object-oriented programming, including how child classes inherit properties and behavior from parent classes, and the role of constructors in this process.

    More Like This

    Use Quizgecko on...
    Browser
    Browser