Ch 12 - Abstract Classes Flashcards

What is an abstract class?

An abstract class can be instantiated as an object.

Will a program that catalogs the types of trees in a forest benefit from an abstract class?

A program that catalogs trees with a different size estimation for each species will benefit from an abstract class.

A program that maintains a grocery list will benefit from an abstract class.

What is a concrete class?

What is an abstract method?

If a subclass does not implement an abstract method, then the subclass must also be defined as abstract.

An abstract class cannot be instantiated because it has missing methods.

An abstract class can include both method signatures for abstract methods and complete code for non-abstract methods.

UML uses italics to denote abstract classes.

Abstract classes provide compile-time polymorphism.

What is an interface?

A class can implement multiple interfaces.

What keyword is needed to create an interface?

How do you implement an interface in a class?

What is an abstract class?

What do interfaces define?

What is an abstract class's role regarding default variables?

What does an interface provide?

An abstract class serves as a blueprint for subclasses, guiding their design but cannot be instantiated.
Subclasses are required to implement the behaviors specified by the abstract class to become concrete classes.
Abstract classes may include both abstract methods (without implementation) and concrete methods (with implementation).
If a subclass does not implement all abstract methods, it must also be declared as abstract.

Cannot create objects of abstract classes due to missing methods.
Denoted in UML using italics to distinguish them from concrete classes.
Facilitate runtime polymorphism, allowing for abstract method calls without knowing the concrete class implementing them.

A concrete class is one that is fully implemented and can be instantiated as an object.

An abstract method is a method defined in an abstract class that subclasses must implement to be concrete.

An interface defines a set of methods that must be implemented by any implementing class.
A class can implement multiple interfaces, enabling multiple inheritance of type.
Use the keyword interface in the class definition to create an interface.
Interfaces provide default variables and static final fields without restricting subclass inheritance.
Unlike abstract classes, interfaces do not provide any implementation code.

Abstract classes are suitable when you want to provide default code and properties for subclasses.
Interfaces are best used when you want to enforce certain behaviors across unrelated classes.