Deck 7: Inheritance

Question 1

A base class is synonymous with a:
(a)Child class
(b)Parent class
(c)Derived class
(d)Sub class

Answer 1

B

Question 2

If an instance variable is not modified by public,protected or private then it is said to have:
(a)Package access
(b)Default access
(c)Friendly access
(d)All of the above

Answer 2

D

Question 3

The special syntax for invoking a constructor of the base class is:
(a)super()
(b)base()
(c)parent()
(d)child()

Answer 3

A

Question 4

A super class is also called a
(a)derived class
(b)dominant class
(c)sub class
(d)base class

Question 5

When you define a derived class,you give only the added instance variables and the added methods as well as all the methods from the base class.

Question 6

What does a derived class automatically inherit from the base class?
(a)instance variables
(b)static variables
(c)public methods
(d)all of the above

Question 7

Inheritance refers to a very specialized form of a class.

Question 8

A method or instance variable modified by protected:
(a)can not be accessed by name inside its own class definitions.
(b)can not be accessed by name inside any class derived from it.
(c)can not be accessed by name in the definition of any class in the same package.
(d)can not be accessed by name in any other class (that is,other than classes named in a-c.).

Question 9

The keyword extends indicates:
(a)encapsulation
(b)polymorphism
(c)inheritance
(d)none of the above

Question 10

The equals method for a class should have _________ as the type of its one parameter.
(a)String
(b)Object
(c)Integer
(d)Double

Question 11

In using the keyword this in place of super(),the invocation of this must be the ___________ action taken by the constructor.
(a)first
(b)last
(c)it does not matter
(d)none of the above

Question 12

The Object class contains the method:
(a)getClass()
(b)toString()
(c)equals()
(d)all of the above

Question 13

A derived class contains only public instance variables and public methods from the base class.

Question 14

The class __________ is an ancestor class of all Java classes.
(a)String
(b)Object
(c)Math
(d)JFrame

Question 15

If the final modifier is added to the definition of a method,this means:
(a)The method may be redefined in the derived class.
(b)The method may be redefined in the sub class.
(c)The method may not be redefined in the derived class.
(d)None of the above.

Question 16

Inheritance is the process by which a new class - known as a _________ - is created from another class,called the _____________.
(a)base class,derived class
(b)derived class,base class
(c)inherited class,base class
(d)base class,inherited class

Question 17

A derived class is also called a
(a)sub class
(b)super class
(c)base class
(d)all of the above

Question 18

An object of a derived class has the type of the derived class,and it also has the type of the base class,and more generally,has the type of every one of its ___________ classes.
(a)descendant
(b)child
(c)ancestor
(d)sub

Question 19

Inheritance promotes code ___________.
(a)reinvention
(b)reuse
(c)repeats
(d)all of the above

Question 20

A derived class is a class defined by adding instance variables and methods to an existing class.

Question 21

Write Java statements that compares Objects,O1 and O2,using the getClass()method.

Question 22

The call to the base class constructor (super)must always be the last action taken in a constructor definition.

Question 23

Explain what a call to super()does in a constructor of a derived class.

Question 24

What is encapsulation?

Question 25

The keyword extends indicates polymorphism.

Question 26

Explain the difference between method overloading and method overriding.

Question 27

What does the instanceof operator do?

Question 28

Create a test driver to test the functionality of your AlarmClock class created in number 3 above.

Question 29

Explain the modifiers public,protected and private.

Question 30

Define a derived class to represent an alarm clock.Use the Clock class,created in number 2 above,as your base class.

Question 31

What is an "is a" relationship? How does it apply to the world of objects?

Question 32

An instance variable (or method)that is private in a base class is accessible by name in the definition of a method in any other class.

Question 33

What is package access?

Question 34

You may substitute the keyword this for super()to call a constructor of the derived class.

Question 35

What is a "has a" relationship?

Question 36

Private methods of the base class are not available for use by derived classes.

Question 37

Overriding is when a derived class redefines a method from the base class.

Question 38

A constructor for a derived class begins with an invocation of a constructor for the base class.

Question 39

Define a base class to represent a Clock.Your class should have instance variables for hours,minutes and seconds.

Question 40

Explain how parent and child classes are related to base and derived classes.

Question 41

Create a test driver to test the functionality of your Rectangle class created in number 14 above.

Question 42

What are the different ways in which you can check the class of an Object?

Question 43

Create a class to represent a Rectangle.Your class should contain instance variables for length and width,as well as member method to calculate the area and perimeter.