Quiz #2 review

Question 1

What are the three types of relationships that can exist between object?

Answer 1

Inheritance, Containment, and Polymorphism

Question 2

Inheritance definition

Answer 2

“inheriting” code from an already created class. Allows user to add on features to starting classes

Question 3

Which = “is-a” relationship

Answer 3

Inheritance; sailboat is a boat

Question 4

Containment definition

Answer 4

“has-a” relationship; car has-a engine

Question 5

Base Class vs Derived Class

Answer 5

Base class is the starting class while the derived class inherits from the base class

Question 6

Object superclass properties

Answer 6

cannot be inherited from

Question 7

Object superclass methods

Answer 7

Equals, clone, toString

Question 8

overriding definition

Answer 8

child class has the same method as the parent class

Question 9

overloading definition

Answer 9

When a class contains two methods with the same name, but one has constructors while the other acts as the no-args constructor

Question 10

Be able to set up the constructor for a derived class and use the super keyword

Answer 10

Be able to set up the constructor for a derived class and use the super keyword

Question 11

Be able to draw an inheritance hierarchy diagram

Answer 11

Be able to draw an inheritance hierarchy diagram

Question 12

How do you add inheritance or containment to a class?

Answer 12

Class extends subclass

Question 13

Differences between private, protected, public, and no access

Answer 13

private can only be accessed by the class, protected can be accessed by the parent class and child classes, public can be accessed by anyone, and no access means nothing has access. No modifier means any file in the current directory may access

Question 14

private

Answer 14

can only be accessed by the class its contained in

Question 15

protected

Answer 15

can only be accessed by the parent class and any child classes

Question 16

public

Answer 16

anyone can use

Question 17

no access

Answer 17

no access

Question 18

no public/private etc,

Answer 18

can be accessed by any file in the same directory

Question 19

Polymorphism definition

Answer 19

when a program is running, you send off a child object as a parent object and you want the parent object to act like a child

Question 20

When does a ClassCastException occur

Answer 20

When you try to send a parent object into a child

Question 21

abstract classes definition

Answer 21

very general class that’s built to be inherited from. Defines methods with abstract keyword, but does not fill in body.
Any class that inherits must have all abstract methods defined.
Must have at least 1 abstract method

Question 22

final classes definition

Answer 22

opposite of abstract classes.
can never be inherited from.
extends is forbidden.
will never be a “is-a”

Question 23

Interfaces definition

Answer 23

purely abstract class.
never has variables.
all methods are abstract be default.

Question 24

When should you use abstract classes?

Answer 24

When a class is very generic

Question 25

abstract classes examples

Answer 25

vehicle, shape.

Question 26

Can you have multiple classes in the same file?

Answer 26

Yes. however only 1 can/must be public

Question 27

Can you have nested classes?

Answer 27

yes

Question 28

BitSet definition

Answer 28

Array of booleans

Question 29

when are interfaces used?

Answer 29

when creating GUIs

Question 30

Definition of Listener Objects

Answer 30

calls to a method when the user interacts with the program (ex. press a button)

Question 31

What is an inner class?

Answer 31

a class nested inside another class

Question 32

Can an object of an inner class type be instantiated?

Answer 32

Not unless the outer class is fist instantiated

Question 33

What is the default layout
manager for a window?

Answer 33

BorderLayout

Question 34

What are the most common layout manager classes

Answer 34

Grid, flow, border

Question 35

Recursion vs iteration

Answer 35

Iteration is a method using a standard loop, while recursion calls upon itself to loop

Question 36

Advantage and disadvantages of recursion compared to iteration

Answer 36

recursion more elegant
easier to debug
uses more memory

Question 37

example of infinite recursion

Answer 37

calling upon the main method

Question 38

Throwable

Answer 38

superclass for all exception classes, and is where the getMessage() method is defined