Deck 11: Advanced Inheritance Concepts

Question 1

Instead of using the automatic toString() method with your classes, it is usually more useful to write your own ____ version of the toString() method that displays some or all of the data field values for the object with which you use it.

A) overloaded
B) protected
C) static
D) condensed

Answer 1

A

Question 2

The Object class ____ method converts an Object into a String that contains information about the Object.

A) equals()
B) setType()
C) toString()
D) speak()

Answer 2

C

Question 3

The java.lang package contains the Object class and is imported automatically each time a program is written.

Answer 3

True

Question 4

When you assign a variable or constant of one type to a variable of another type, the behavior is called ____.

A) implicit conversion
B) referencing
C) dynamic method binding
D) containing

Question 5

A(n) ____ is not an object, but it points to a memory address.

A) abstract class
B) reference
C) extend
D) interface

Question 6

You sometimes create an abstract class only so you can ____ it to another class.

A) link
B) copy
C) extend
D) abstract

Question 7

When you create a class that uses an interface, you include the keyword extends.

Question 8

A(n) ____ class is one from which you cannot create any concrete objects, but from which you can inherit.

A) abstract
B) inheritance
C) parent
D) final

Question 9

It is common to create an interface when you want a class to implement behavior from more than one parent.

Question 10

An application's ability to select the correct subclass method is known as ____.

A) implementing methods
B) dynamic method binding
C) implicit casting
D) method fixing

Question 11

A good toString() method can be very useful in debugging a program.

Question 12

When you create a subclass of an abstract class, it's important to understand that you are required to code a subclass method to override the empty superclass method that is inherited.

Question 13

While a class can inherit from any abstract superclass, it can only implement one interface.

Question 14

Nonabstract classes from which objects can be instantiated are called constant classes.

Question 15

When you define a class, if you do not explicitly extend another class, your class is an extension of the ____ class.

A) Object
B) super
C) public
D) abstract

Question 16

Abstract classes and interfaces are similar in that you cannot instantiate concrete objects from either one.

Question 17

Java does not allow a class to inherit directly from two or more parents.

Question 18

If you attempt to instantiate an object from an abstract class, you receive an error message from the compiler that you have committed a(n) ____.

A) LogicError
B) InstantiationError
C) SyntaxError
D) ObjectError

Question 19

Which of the following statements creates an array of three Animal references?

A) Animal[] ref = new Animal(3);
B) Animal[] new = ref Animal[3];
C) Animal[] animalRef = new Animal[3];
D) Animal[] ref = extend Animal[3];

Question 20

A class that will be placed in a nondefault package for others to use must be private.

Question 21

The capability to inherit from more than one class is called ____.

A) multiple inheritance
B) collision
C) polyinheritance
D) dynamic method binding

Question 22

The Object class contains a(n) ____________________ method that takes a single argument, which must be the same type as the type of the invoking object.

Question 23

Classes, such as the String class, have their own equals() methods that overload the ____ class method.

A) Object
B) Public
C) Abstract
D) Child

Question 24

Abstract classes and methods appear in ____ in a class diagram.

A) bold
B) all caps
C) italics
D) blue

Question 25

The ___ method is useful in debugging a program because it can be used to display and examine values.

A) finalize()
B) toString()
C) notify()
D) equals()

Question 26

When you create a class and use the implements clause to implement an interface but fail to code one of the interface's methods, the compiler error generated indicates that you must declare your class to be ____.

A) abstract
B) static
C) public
D) related

Question 27

When a class both extends and implements, by convention the ____ clause is last in the class header.

A) extends
B) new
C) implements
D) if

Question 28

In the Java programming language, a package or class library is often delivered to users as a(n) ____________________ file.

Question 29

Which of the following is NOT true regarding abstract methods?

A) Abstract methods must be implemented in child classes.
B) Abstract methods have no body.
C) Abstract methods use the abstract keyword in declarations.
D) Abstract methods are inherited by their children.

Question 30

A(n) ____ looks much like a class, except that all of its methods (if any) are implicitly public and abstract.

A) hash code
B) package
C) collision
D) interface

Question 31

Java's Object class contains a public method named ____ that returns an integer representing the hash code.

A) length()
B) hashCode()
C) hcode()
D) toString()

Question 32

When you create a new subclass in Java, neither the superclass source code nor the superclass _____ is changed.

A) bytecode
B) object
C) argument
D) possession

Question 33

____ compress the data they store, which reduces the size of archived class files.

A) Dynamic method bindings
B) JAR files
C) Type-import-on-demand declarations
D) Interfaces

Question 34

The Object class equals() method returns a(n) ____ value indicating whether the objects are equal.

A) int
B) equals
C) null
D) boolean

Question 35

If you do not specify a package for a class, it is placed in an unnamed ____ package.

A) system
B) language
C) default
D) general

Question 36

When you create a number of classes that inherit from each other, as well as multiple interfaces that you want to implement with these classes, you often will find it convenient to place these related classes in a(n) ____________________.

Question 37

If Java did not allow you to ____ classes, you would need to create every part of a program from scratch.

A) extend
B) override
C) abstract
D) import

Question 38

In other programming languages, such as C++, abstract classes are known as ____________________ classes.

Question 39

If you provide an empty method within an abstract class, the method is an abstract method even if you do not explicitly use the keyword ____________________ when defining the method.

Question 40

____ provides a calculated hexadecimal number that is used to identify an object.

A) Method binding
B) A hash code
C) Implicit conversion
D) Ad-hoc polymorphism

Question 41

Why do many programmers consider multiple inheritance to be a difficult concept?

Question 42

Match each term with the correct statement below.
a.dynamic method binding
f.-d option
b.collision
g.java.lang
c.GregorianCalendar
h.public, static, and final
d.multiple inheritance
i.interface
e.equals() method
An alternative to multiple inheritance available in Java

Question 43

Match each term with the correct statement below.
a.dynamic method binding
f.-d option
b.collision
g.java.lang
c.GregorianCalendar
h.public, static, and final
d.multiple inheritance
i.interface
e.equals() method
A concrete class that extends the abstract class Calendar

Question 44

Match each term with the correct statement below.
a.dynamic method binding
f.-d option
b.collision
g.java.lang
c.GregorianCalendar
h.public, static, and final
d.multiple inheritance
i.interface
e.equals() method
Considers two objects of the same class to be equal only if they have the same hash code

Question 45

What is an abstract class? Give an example and explain how it works.

Question 46

Match each term with the correct statement below.
a.dynamic method binding
f.-d option
b.collision
g.java.lang
c.GregorianCalendar
h.public, static, and final
d.multiple inheritance
i.interface
e.equals() method
Data fields in an interface

Question 47

Match each term with the correct statement below.
a.dynamic method binding
f.-d option
b.collision
g.java.lang
c.GregorianCalendar
h.public, static, and final
d.multiple inheritance
i.interface
e.equals() method
Contains the Object class

Question 48

Compare and contrast abstract classes and interfaces.

Question 49

Describe the two method types programmers of an abstract class can include.

Question 50

Match each term with the correct statement below.
a.dynamic method binding
f.-d option
b.collision
g.java.lang
c.GregorianCalendar
h.public, static, and final
d.multiple inheritance
i.interface
e.equals() method
The javac command to specify a directory

Question 51

When you create a useful, extendable superclass, you and other future programmers gain what advantages?

Question 52

When a superclass is abstract, you cannot instantiate objects of a superclass. How can you use a superclass abstract object?

Question 53

Give an example of how you can create an interface to have a class implement behavior from more than one parent.

Question 54

What is the toString() method used for and how is it used?

Question 55

How is the Object class equals() method implemented?

Question 56

When you create classes for others to use, why would you not want to provide the users with your source code in the files with .java extensions?

Question 57

Match each term with the correct statement below.
a.dynamic method binding
f.-d option
b.collision
g.java.lang
c.GregorianCalendar
h.public, static, and final
d.multiple inheritance
i.interface
e.equals() method
Prohibited in Java

Question 58

Match each term with the correct statement below.
a.dynamic method binding
f.-d option
b.collision
g.java.lang
c.GregorianCalendar
h.public, static, and final
d.multiple inheritance
i.interface
e.equals() method
The correct subclass method is attached to the application

Question 59

Match each term with the correct statement below.
a.dynamic method binding
f.-d option
b.collision
g.java.lang
c.GregorianCalendar
h.public, static, and final
d.multiple inheritance
i.interface
e.equals() method
A class-naming conflict

Question 60

What is dynamic method binding and why is it used?

Question 61

What are the three ways in which you can compare abstract classes and interfaces?

Question 62

public abstract class Shape
{
private int length;
private int width;
private int height;
____
}
Using the above code, create the statement in the shaded line that will create an abstract calculateArea() method in the abstract Shape class.

Question 63

What are the advantages to creating a useful, extendable superclass?

Question 64

public class CarReference
{
public static void main(String[] args)
{
Car carRef;
____
carRef.color();
}
}
Suppose you have created a Car class and Honda and Ford subclasses. Using the above code, complete the highlighted statement to create a new Honda object that is assigned to the Car reference.

Question 65

public class Animal
{
}
public class Animal extends Object
{
}
The two class declarations above have identical outcomes. Explains why this is the case.

Question 66

public abstract class Car
{
private String model;
public abstract void color();
public String getModel()
{
return model;
}
public void setModel(String modelName)
{
model = modelName;
}
}
public class Honda extends Car
{
public void color()
{
System.out.println("red");
}
}
public class Ford extends Car
{
public void color()
{
System.out.println("blue");
}
}
public class MyCars
{
public static void main(String[] args)
{
Honda myHonda = new Honda();
Ford myFord = new Ford();
myHonda.setModel("My Honda is ");
myFord.setModel("My Ford is ");
System.out.print(myHonda.getModel());
myHonda.color();
System.out.print(myFord.getModel());
myFord.color();
}
}
Using the above code, describe the output that will appear when the program is executed.

Question 67

public interface FindTheError
{
void firstMethod(int anIntNum)
{
System.out.println("Did you find the error?");
}
}
What is the problem with the above interface? How would you correct the interface?

Question 68

public abstract class Car
{
private String model;
public abstract void color();
public String getName()
{
return model;
}
public void setName(String carModel)
{
model = carModel;
}
}
Using the code above, would it be possible to create a class in which you declare a Car object with the statement Car myCar = new Car("Honda");?
Explain why or why not.

Question 69

public abstract class Car
{
private String model;
public abstract void color();
public String getModel()
{
return model;
}
public void setModel(String modelName)
{
model = modelName;
}
}
public class Honda extends Car
{
public void color()
{
System.out.println("red");
}
}
public class Ford extends Car
{
public void color()
{
System.out.println("blue");
}
}
public class MyCars
{
public static void main(String[] args)
{
Honda myHonda = new Honda();
Ford myFord = new Ford();
myHonda.setModel("My Honda is ");
myFord.setModel("My Ford is ");
System.out.print(myHonda.getModel());
myHonda.color();
System.out.print(myFord.getModel());
myFord.color();
}
}
In the above code, the myHonda.getModel() and myHonda.color() method calls produce different output from when the same methods are used with myFord. Explain why this is the case.

Question 70

public abstract class Car
{
private String model;
public abstract void color();
public String getModel()
{
return model;
}
public void setModel(String modelName)
{
model = modelName;
}
}
The above code creates a generic abstract class named Car with an abstract color() method. Using the code below, fill in the shaded statements in order to create a Honda class that extends Car.
public class ____ extends ____
{
public void ____
{
System.out.println("I like your red car!");
}
}