Deck 10: Introduction to Inheritance

Question 1

The class used as a basis for inheritance is the ____ class.

A) child
B) extends
C) base
D) derived

Answer 1

C

Question 2

In a UML diagram, an inheritance relationship is indicated with an arrow that points from the original class  to the descendant class  .

Answer 2

False

Question 3

A class diagram consists of a rectangle divided into three sections.

Answer 3

True

Question 4

____ is a mechanism that enables one class to acquire all the behaviors and attributes of another class.

A) Inheritance
B) Polymorphism
C) Encapsulation
D) Override

Question 5

Arrows used in a ____ to show inheritance relationships extend from the descendant class and point to the original class.

A) method diagram
B) UML diagram
C) virtual method call
D) composition

Question 6

Subclasses are more specific than the superclass they extend.

Question 7

It is useful to override the parent class members when the superclass data fields and methods are not completely appropriate for the subclass objects.

Question 8

When you use the method name with a child object, the parent's version of the method is used.

Question 9

When a protected data field or method is created, it can be used within its own class or in any classes extended from that class; but it cannot be used by outside classes.

Question 10

A nonstatic method cannot  override a static member  of a parent class.

Question 11

An error is generated by the compiler when you attempt to override a static method with a nonstatic method.

Question 12

When you create any subclass object, the subclass constructor  must execute first, and then the superclass constructor  executes.

Question 13

Sometimes the superclass data fields and methods are not entirely appropriate for the subclass objects; in these cases, you want to ____ the parent class members.

A) negate
B) overrule
C) override
D) hide

Question 14

If a programming language does not support ____, the language is not considered object-oriented.

A) syntax
B) applets
C) loops
D) polymorphism

Question 15

By convention, a class diagram contains the ____ following each attribute or method.

A) data field
B) argument
C) data type
D) class

Question 16

When you create a class by making it inherit from another class, the new class automatically contains the data fields and _____ of the original class.

A) fonts
B) methods
C) class names
D) arrays

Question 17

The ability to use inheritance in Java makes programs easier to write, ____, and more quickly understood.

A) faster
B) more secure
C) more robust
D) less error prone

Question 18

You cannot declare a class to be final .

Question 19

You use the keyword ____ to achieve inheritance in Java.

A) inherit
B) extends
C) super
D) public

Question 20

____ polymorphism is the ability of one method to work appropriately for subclasses of the same parent class.

A) Subtype
B) Name
C) Supertype
D) Override

Question 21

Which of the following statements depicts the valid format to call a superclass constructor from a subclass constructor?

A) superclass(name, score);
B) subclass(name, score);
C) extends(name, score);
D) super(name, score);

Question 22

When you create a class and do not provide a(n) ____, Java automatically supplies you with a default one.

A) constructor
B) argument
C) header
D) name

Question 23

The classes you create in ____________________ programming languages can inherit data and methods from existing classes.

Question 24

You can use the ____ modifier with methods when you don't want the method to be overridden.

A) override
B) access
C) final
D) end

Question 25

You are never aware that ____ is taking place; the compiler chooses to use this procedure to save the overhead of calling a method.

A) information hiding
B) polymorphism
C) overriding
D) inlining

Question 26

Which statement correctly declares a sedan object of the Car class?

A) sedan Car = new sedan();
B) sedan Car = new sedan();
C) Car sedan = new Car();
D) new sedan() = Student;

Question 27

When you employ ____, your data can be altered only by the methods you choose and only in ways that you can control.

A) virtual method calls
B) polymorphism
C) information hiding
D) inlining

Question 28

If a ____ method has the same name as a parent class method and you use the name with a child class object, the child method hides the original.

A) final
B) static
C) protected
D) private

Question 29

An advantage to making a method ____________________ is that the compiler knows there will be only one version of the method.

Question 30

Usually, the subclass constructor only needs to initialize the ____ that are specific to the subclass.

A) objects
B) data fields
C) methods
D) constructors

Question 31

Using the keyword ____ provides you with an intermediate level of security between public and private access.

A) protected
B) this
C) super
D) secure

Question 32

In most Java classes, the keyword private precedes each data field, and the keyword ____________________ precedes each method.

Question 33

Programmers and analysts sometimes use a graphical language to describe classes and object-oriented processes. This language is called ___________________________________.

Question 34

The term ____________________ means "many forms."

Question 35

Which of the following statements will create a class named Red that is based on the class Color ?

A) public class Red extends Color
B) public Red class extends Color
C) public Color class expands Red
D) public extend Red class Color

Question 36

If jrStudent is an object of Student , which of the following statements will result in a value of true ?

A) Student = instanceof jrStudent
B) jrStudent instanceof Student
C) instanceof Student = jrStudent
D) Student instanceof jrStudent

Question 37

The methods in a subclass can use all of the data fields and methods that belong to its parent, with one exception: ____ members of the parent class are not accessible within a child class's methods.

A) private
B) public
C) final
D) protected

Question 38

You can use the keyword _______ within a method in a derived class to access an overridden method in a base class.

A) sub
B) this
C) protected
D) super

Question 39

You would like to make a member of a class visible in all subclasses regardless of what package they are in. Which one of the following keywords would achieve this?

A) private or protected
B) private
C) protected
D) public

Question 40

When you create parent and child classes of your own, the child classes use ____ constructors.

A) two
B) three
C) four
D) six

Question 42

What is information hiding and how is it used?

Question 43

Create a class named Student that contains methods getGPA() , setIDNum() , and setGPA() . Be sure to declare variables and methods appropriately as public or private.

Question 44

What happens when you write your own constructor in Java and what must you pay attention to?

Question 45

What is the difference between derived classes and base classes when considering two classes that inherit from each other?

Question 46

How is the keyword protected used?

Question 47

You have a Student class with a constructor that requires two arguments: a character "F" for Freshman and an integer "2020" for the year. Create a Freshman class that is a subclass of Student with a constructor for Freshman . Include the initial super() statement and include a comment that reads "//Other statements go here".

Question 48

How are real-life examples of inheritance similar to object-oriented programming inheritance?

Question 49

      
Use the above code and sections labeled 1, 2, and 3 to answer the following:
Identify the labeled section that is the constructor for the Bicycle class, identify the section of fields of the Bicycle class, and identify the Bicycle class methods.

Question 50

What are virtual method calls?

Question 51

What does polymorphism mean in Java programming?

Question 52

What is the process of inlining and how is it accomplished in Java?

Question 53

Create a class named Employee with a name and a salary . Make a class named Manager that inherits from Employee with an instance field named department . Supply a toString() method that prints the manager's name, department, and salary. Make another class named Director that inherits from Manager with an instance field named stipendAmount . Supply the toString() method for Director that prints all of its instance variables. Also, write a program named myOutput that instantiates an object of each of the classes and invokes the toString() method of each of the objects.

Question 54

class Animal
{  
    void myDog()  
    {  
        System.out.println("Animal stuff");  
    }  
}  
        
      
class Dog extends Animal
{  
     void mydog()  
    {  
        System.out.println("Dog stuff");  
    }  
    public static void main(String args[])  
    {  
        Dog d = new Dog();  
        d.myDog();  
        super.myDog();  
    }  
}
The above code gives a compiler error stating that the non-static variable super cannot be
referenced from a static context super.myDog(); . Explain why the error occurs and describe what changes you could make for the code to be executable.

Question 55

Using a class named Student , write the statement to create a yearOne object of the Student class.

Question 56

When you instantiate an object that is a member of a subclass, how many constructors are called?

Question 57

Write the statement to create a class header with a superclass-subclass relationship, with Vehicle as the superclass and Subaru as the subclass.

Question 58

public HourlyEmployee(char dept, double rate, int hours)
{
     ---- code here ----
}
Given the overloaded constructor above, write the appropriate statement that calls the superclass constructor  and passes the indicated arguments to the superclass constructor.

Question 59

class InstanceofDemo
{
    public static void main(String[] args)
   {
        Parent object1 = new Parent();
        Parent object2 = new Child();
        System.out.println("object1 instanceof Parent: "
            + (obj1 instanceof Parent));
        System.out.println("object1 instanceof Child: "
            + (obj1 instanceof Child));
        System.out.println("object1 instanceof MyInterface: "
            + (obj1 instanceof MyInterface));
        System.out.println("object2 instanceof Parent: "
            + (obj2 instanceof Parent));
        System.out.println("object2 instanceof Child: "
            + (obj2 instanceof Child));
        System.out.println("object2 instanceof MyInterface: "
            + (obj2 instanceof MyInterface));
     }
}
The above code defines a parent class (named Parent ), a simple interface (named MyInterface ), and a child class (named Child ) that inherits from the parent and implements the interface.
Following program execution, what will be the output of the six println statements?

Question 60

What are the parts of a class diagram and how would you use them?

Question 61

What are the three types of methods that you cannot override in a subclass?

Question 62

The above code will generate an error message when compiling. Explain the error message and why it occurs.

Question 63

The UML diagram above derives a subclass called EmployeeWithTerritory from the superclass Employee . Describe what variables and methods the class EmployeeWithTerritory  inherits from the superclass Employee .  Also, describe any variables and public methods defined by the subclass EmployeeWithTerritory .

Question 64

Will the above code compile correctly? Why or why not? Explain your answer.

Question 65

public class ASuperClass
{
   public ASuperClass()
   {
      System.out.println("In superclass constructor");
   }
}
public class ASubClass extends ASuperClass
{
   public ASubClass()
   {
      System.out.println("In subclass constructor");
   }
}
public class DemoConstructors
{
   public static void main(String[] args)
   {
      ASubClass child = new ASubClass();
   }
}
Given the above code, what will the output be when DemoConstructors executes?

Question 66

class Vehicle {}
public class Car extends Vehicle
{
   public static void main(String args[])
   {
      Vehicle myCar = new Car();
      boolean result =  myCar instanceof Car;
      System.out.println(result);
   }
}
The above code uses the instanceof operator to determine whether an object is a member of a class. What will be the output following execution?