Inheritance and Method Overriding Quiz

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Questions and Answers

What type of relationship exists between the PhysicsTeacher class and the Teacher class?

PhysicsTeacher is unrelated to Teacher
PhysicsTeacher is a composition of Teacher
PhysicsTeacher is an aggregation of Teacher
PhysicsTeacher is a subclass of Teacher (correct)

Which output will be displayed when the main method of PhysicsTeacher is executed?

Teacher, Physics, John
Physics, John, Teacher
John, Teacher, Physics (correct)
Physics Teacher, John, Teacher

If a member of the Teacher class is declared as private, how can it be accessed in PhysicsTeacher?

By changing its access modifier in the Teacher class
Using public or protected getter and setter methods (correct)
Directly through the object of PhysicsTeacher
It cannot be accessed in any way

Which of the following best describes the concept of inheritance in the context provided?

Inheritance enables a child class to inherit properties and methods from a parent class. (C) Signup and view all the answers

What will happen if the mainSubject variable is declared as private in the PhysicsTeacher class?

It can be accessed within the same class without any issues. (B) Signup and view all the answers

What value is returned by the getCollegeName() method when called on an instance of JavaExample?

John (B) Signup and view all the answers

Which access specifier allows access only within the class itself and in its subclasses?

Protected (B) Signup and view all the answers

What happens when the object of the subclass JavaExample is created?

The superclass constructor is invoked first. (C) Signup and view all the answers

What type of method is does() in the Teacher class?

Package-private (A) Signup and view all the answers

How can the constructor of a superclass be explicitly called in a subclass?

Using the super keyword as the first statement. (A) Signup and view all the answers

Which of the following statements is true regarding the JavaExample class?

It can modify the designation using a method. (A), It inherits non-static methods from the Teacher class. (B) Signup and view all the answers

What is printed when obj.does() is called?

Teaching (C) Signup and view all the answers

Which statement about access specifiers is correct?

Protected members are accessible in subclasses and the same package. (D) Signup and view all the answers

What does the method sound() in the Horse class override?

The generic sound() method from the Animal class (B) Signup and view all the answers

What is an example of runtime polymorphism in the given code?

Calling the sound() method from the Animal object (A) Signup and view all the answers

What does polymorphism allow in programming?

To define one method signature with different implementations (D) Signup and view all the answers

Which of the following statements is true about method overloading?

It allows methods to perform different operations based on input parameters (D) Signup and view all the answers

What will be the output of the following code snippet? Animal obj = new Cat(); obj.sound();

Meow (C) Signup and view all the answers

Why is it important not to call the generic sound() method in the given context?

Each subclass may implement sound() differently (B) Signup and view all the answers

What concept allows the sound() method to behave differently for different animal types?

Polymorphism (D) Signup and view all the answers

Which class serves as the superclass in the provided examples?

Animal (B) Signup and view all the answers

What is the output when a new object of JavaExample is created?

Constructor of Parent followed by Constructor of Child (D) Signup and view all the answers

What does the super keyword do in the context of method overriding?

It invokes the method from the parent class. (C) Signup and view all the answers

What is the main action of polymorphism in Object Oriented Programming?

To allow multiple implementations of a method. (C) Signup and view all the answers

What will be printed when the disp() method is called on a JavaExample object?

Child Method followed by Parent Method (A) Signup and view all the answers

How is method overriding achieved in Java?

By defining the same method in the child class. (A) Signup and view all the answers

In an Animal class scenario, what does each subclass do with the sound() method?

Implements its own version of sound() with unique sounds. (C) Signup and view all the answers

What does the output indicate when both child and parent constructors run?

The child class constructor must call the parent constructor. (A) Signup and view all the answers

Which concept allows deriving classes to define specific behaviors in Java?

Inheritance (B) Signup and view all the answers

What is the primary characteristic of the method overloading demonstrated in the Overload class?

Methods can have different parameter types or numbers. (A) Signup and view all the answers

At what point is the method to be called determined in method overloading?

At compile time based on the return type. (A) Signup and view all the answers

What will be the output of the method call `Obj.demo(5.5)`?

double a: 5.5 (B) Signup and view all the answers

What does the `result` variable hold after executing the method call `result = Obj.demo(5.5)`?

30.25 (A) Signup and view all the answers

How many methods are overloaded in the Overload class?

3 (C) Signup and view all the answers

Study Notes

Inheritance

Inheritance establishes an "IS-A" relationship between a child class and a parent class.
A child class inherits public and protected members and methods from its parent class.
Private members of the parent class are inaccessible to the child class directly but can be accessed via public or protected getter and setter methods in the parent class.
Constructors in subclasses invoke the superclass's default constructor by default; this happens top-down. The superclass constructor can be explicitly called using the super keyword, but it must be the first statement within the subclass constructor.
Multiple super keywords to access ancestors beyond the direct parent are not allowed.

Method Overriding

Method overriding occurs when a child class declares a method with the same signature as a method in the parent class.
When called from a child class object, the child class's version of the method executes.
The parent class's method can be called using the super keyword.

Polymorphism

Polymorphism enables a single action to be performed in multiple ways.
Runtime polymorphism (dynamic dispatch) determines which method to call at runtime based on the object type. Example: An Animal class with a sound() method, overridden in subclasses like Horse and Cat to produce different sounds.
Compile-time polymorphism (method overloading) is resolved at compile time based on the method signature (number and type of arguments). Example: A class with multiple methods having the same name but different parameters.

Access Specifiers

public: Accessible from anywhere.
protected: Accessible within the class itself and its subclasses.
private: Accessible only within the class itself.

Example Code Explanations

The provided Java code demonstrates inheritance, method overriding and polymorphism using Teacher, PhysicsTeacher, JavaExample, Animal, Horse, and Cat classes. The examples showcase how these concepts work and how to use the super keyword. The code also demonstrates method overloading with the Overload and MethodOverloading classes.
The output of each code snippet is provided showing the expected results based on inheritance and method overriding behaviors.

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Description

Test your understanding of inheritance and method overriding concepts in object-oriented programming. This quiz covers the principles of 'IS-A' relationships, access control, and method overriding in child and parent classes.