Chapter 13 - Abstract Classes and Interfaces

Questions and Answers

What is an abstract class?

A class that has concrete methods.

A class that can have instances.

A class that cannot have instances. (correct)

A class that must be instantiated.

What is an abstract method?

A method signature without implementation.

What does a deep copy do when cloning an object?

Clones all its fields recursively.

What is an interface in Java?

A special class with only constants and method declarations. Signup and view all the answers

What is a marker interface?

An empty interface that signifies shared properties. Signup and view all the answers

A class may extend multiple superclasses.

False Signup and view all the answers

What happens in a shallow copy when cloning an object?

All its fields are copied. Signup and view all the answers

A class can extend only one superclass.

True Signup and view all the answers

What is a subinterface?

An interface inherited from another interface. Signup and view all the answers

Study Notes

Abstract Classes

Abstract classes are superclasses designed to have common features shared by subclasses.
Declared using the abstract modifier, these classes cannot be instantiated (no object creation using new).
Contain both data fields and methods similar to regular classes.

Abstract Methods

An abstract method has a signature but lacks an implementation.
Denoted with the abstract modifier and must exist within an abstract class.
Subclasses that extend an abstract class must implement all abstract methods, whether they are used or not.

Deep Copy

Cloning an object through a deep copy means recursively cloning all its fields.
Ensures that the new object is entirely independent of the original object.

Interfaces

An interface functions like a special class; each one compiles into a separate bytecode file.
Instances of an interface cannot be created.
Similar to abstract classes, interfaces can have data (which must be constants) and method declarations without implementations.
Java enforces single inheritance, where a class can inherit from only one superclass, but interfaces allow for multiple inheritance by implementing multiple interfaces.

Marker Interface

A marker interface is an empty interface serving to indicate that all implementing classes share certain properties or behaviors.

Multiple Inheritance

This refers to a class extending multiple superclasses, allowing for more complex behavior and functionality.

Shallow Copy

In a shallow copy, all fields of the object are copied, but nested objects are not recursively cloned.

Single Inheritance

A class can extend only one superclass, maintaining a straightforward hierarchy.

Subinterface

A subinterface is an interface that is inherited from another interface, allowing for further specialization.

Description

This quiz focuses on the concepts of abstract classes and interfaces as presented in Chapter 13. Students will explore the definitions, characteristics, and significance of these abstract components in object-oriented programming. Enhance your understanding of how these principles apply to class design.