Ch 10 - Gaddis

Question 1

Inheritance

Answer 1

Inheritance allows a new class to extend an existing class. The new class inherits the members of the class it extends. The Java API has a class named Object, which all other classes directly or indirectly inherit from.

Question 2

super

Answer 2

The super keyword refers to an object’s superclass. You can use the super key word to call a superclass constructor.

Question 3

Overriding superclass methods

Answer 3

A subclass may have a method with the same signature as a superclass method. In such a case, the subclass method overrides the superclass method.

Question 4

Protected members

Answer 4

Protected members of a class may be accessed by methods in a subclass, and by methods in the same package as the class.

Question 5

Chains of inheritance

Answer 5

A superclass can also inherit from another class.

Question 6

Polymorphism

Answer 6

A superclass reference variable can reference objects of a subclass.

Question 7

Abstract classes & abstract methods

Answer 7

An abstract class is not instantiated, but other classes extend it. An abstract method has no body and must be overridden in a subclass.

Question 8

Interface

Answer 8

An interface specifies behavior for a class.

Question 9

Anonymous inner classes

Answer 9

An inner class is a class that is defined inside another class. An anonymous inner class is an inner class that has no name. An anonymous inner class must implement an interface, or extend another class.

Question 10

Functional interfaces & lambda expressions

Answer 10

A functional interface is an interface that has one abstract method. You can use a special type of expression, known as a lambda expression, to create an object that implements a functional interface (Java 8).