Chapter 5

Question 1

What is the definition of a class in Java?

Answer 1

A class is a blueprint for an object.

Question 2

What does an object have in terms of state and behavior?

Answer 2

State = attributes = data; Behaviors = operations = class methods.

Question 3

What are the two types of constructors in Java?

Answer 3

• Default constructor
• Parameterized constructor.

Question 4

What is the purpose of the toString method in Java?

Answer 4

The toString method returns a string that contains the data in the object.

Question 5

What are accessors and mutators?

Answer 5

• Accessor: returns the current value of a variable.
• Mutator: changes the value of a variable.

Question 6

What is instance data in the context of a class?

Answer 6

Instance data refers to data that is unique to each object instance.

Question 7

What does the final modifier do in Java?

Answer 7

The final modifier is used to define constants.

Question 8

How many visibility modifiers does Java have and what are they?

Answer 8

Java has three visibility modifiers: * public
* protected
* private.

Question 9

What is the difference between public and private visibility in Java?

Answer 9

• Public: can be referenced anywhere.
• Private: can be referenced only within that class.

Question 10

What is meant by local data in Java?

Answer 10

Local data refers to data declared within a method that can only be used in that method.

Question 11

What is the scope of data in a Java program?

Answer 11

The scope of data is the area in a program where that data can be referenced.

Question 12

What is the purpose of a method header?

Answer 12

A method header begins with the method’s name, return type, and parameter list.

Question 13

What does a return statement do in a method?

Answer 13

The return statement specifies the value that will be returned to the calling location.

Question 14

What are static methods and how are they invoked?

Answer 14

Static methods are invoked through their class name without needing to create an object first.

Question 15

What happens when a variable is declared as static?

Answer 15

Only one copy of the variable exists, shared among all objects instantiated from the class.

Question 16

What is the this reference in Java?

Answer 16

The this reference allows an object to refer to itself.

Question 17

What is method decomposition?

Answer 17

Method decomposition is breaking down a complex problem into smaller, manageable methods.

Question 18

How are parameters passed in Java methods?

Answer 18

Parameters are passed by value, meaning a copy of the actual parameter is stored in the formal parameter.

Question 19

What is the structure of a UML class diagram?

Answer 19

A UML class diagram consists of class names, attributes (data), and operations (methods).

Question 20

What do solid arrows represent in UML diagrams?

Answer 20

Solid arrows show that one class uses another by calling its methods.

Question 21

What are service methods in Java?

Answer 21

Service methods are public methods that provide the object’s services and can be invoked by clients.

Question 22

What is a support method in Java?

Answer 22

A support method assists a service method and should be declared with private visibility.

Question 23

Fill in the blank: A _______ method is used to give values to the instance data when the object is initially created.

Answer 23

constructor

Question 24

True or False: Instance variables exist as long as the object exists.

Answer 24

True

Question 25

How are parameters in a Java method passed?

Answer 25

Parameters are passed by value

A copy of the actual parameter is stored into the formal parameter in the method header

Question 26

What is the relationship between actual and formal parameters when passing objects to methods?

Answer 26

They are aliases of each other

An object is passed to a method by reference

Question 27

What is method overloading?

Answer 27

Giving a single method name multiple definitions

The signature of each overloaded method must be unique

Question 28

What does the signature of an overloaded method include?

Answer 28

The number, type, and order of the parameters

The return type is not part of the method signature

Question 29

True or False: The return type of the method is part of the method signature in Java.

Answer 29

False

Question 30

What determines which overloaded method is invoked?

Answer 30

The compiler analyzes the parameters

It considers the number, type, and order of parameters

Question 31

Fill in the blank: The method _______ is overloaded in Java.

Answer 31

println

Question 32

What is the purpose of overloaded constructors?

Answer 32

To provide multiple ways to initialize a new object

Question 33

What is the difference between passing a primitive variable versus an object as a parameter?

Answer 33

Primitive variables are passed by value, objects are passed by reference

This affects how changes to parameters in methods are reflected

Question 34

What are the syntax rules for overloaded methods?

Answer 34

The method names must be the same, but the signatures must differ

This includes differing in the number, type, or order of parameters

Question 35

What are some key topics expected on the exam from Chapter 5?

Answer 35

Creating a class, constructors, accessors, mutators, toString, testing a class, writing methods, calling/using methods