Questions and Answers
The process of inheritance should establish a(n) ___________________ relationship.
is-a
The original class that is used to derive a new class using inheritance is called ____________________.
all of the above
__________ occurs when a child class defines a method with the same signature as a method in the parent class.
Overriding
In order for derived classes to have access to encapsulated data members and methods of superclasses, the data members and methods should be declared using the ____________________ modifier.
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A child class can access private members of a parent class by __________________.
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When a variable declared in a subclass has the same name as a variable declared in a superclass, it is called a _______________ variable.
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A(n)______________________ class represents a generic concept in a class hierarchy.
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A class declared as final _________________________________.
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Which of the following key words indicates a method that cannot be overridden in a derived class?
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To invoke a parent's constructor in a subclass, we use the ______________ method.
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Which of the following statements is not a general inheritance practice that you should keep in mind in the design of a program?
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All Java classes are subclasses of the ___________________ class.
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When designing a class hierarchy, it is important that common features be ________________________.
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Which of the following methods are included in every class created in Java by inheritance?
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Of the classes below, the one that is most likely to be declared abstract is _________________.
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A parent class object must be created before objects of a child class can be created.
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Private members of a parent class are inherited by child classes.
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Java supports multiple inheritance.
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In Java, a subclass can only extend one parent class.
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A child class is allowed to define a method with the same name and parameter list as a method in the parent class.
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A child class is allowed to declare a variable with the same name as one that is contained in the parent class.
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Study Notes
Inheritance Basics
- Inheritance establishes an "is-a" relationship between classes.
- The original class in inheritance is referred to as the superclass, base class, or parent class.
Method Overriding
- Occurs when a child class defines a method with the same signature as a method in the parent class.
- This is known as overriding, which allows customization of inherited methods.
Access Modifiers
- To allow derived classes access to superclass members, those members must be declared as protected.
- Private members of a parent class cannot be accessed directly by child classes; accessibility is limited to public accessor and mutator methods.
Variable Shadowing
- When a subclass declares a variable with the same name as one in the superclass, it is termed as a shadow variable.
Abstract Classes
- An abstract class represents a generic concept in a class hierarchy, which cannot be instantiated directly.
- Abstract classes help define a common interface for derived classes.
Final Classes and Methods
- A final class cannot be subclassed, ensuring its implementation remains unchanged.
- Methods marked as final cannot be overridden in derived classes.
Calling Parent Constructors
- To invoke a parent class's constructor from a subclass, the keyword "super" is used.
General Inheritance Practices
- Derived classes should maintain an "is-a" relationship with their parent classes.
- Avoid using the final keyword unnecessarily for parent classes to allow flexibility in design.
Class Hierarchy Design
- Common features should be defined higher in the class hierarchy to promote code reusability and simplicity.
- Every Java class inherits from the Object class, which provides essential methods like toString.
Abstract Classes Example
- The class "Animal" is a typical candidate for being declared as abstract since it serves as a base for various specific animal subclasses.
Statements on Inheritance
- A parent class object does not need to be created for child class instances to exist.
- Private members are inherited by child classes, but cannot be accessed directly.
- Java does not support multiple inheritance; a subclass can extend only one parent class.
- Child classes can define methods and variables with the same name as those in parent classes, allowing method overriding and variable shadowing.
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Description
This quiz covers fundamental concepts of object-oriented programming, including inheritance, method overriding, access modifiers, variable shadowing, and abstract classes. Test your understanding of how these principles create relationships and structure within your code.
