Question 1

Match between columns
                        Premises: Data fields in an interface
A class-naming conflict
A method that is inherited
An alternative to multiple inheritance available in Java
Considers two objects of the same class to be equal only if they have the same hash code
The correct subclass method is attached to the application
Prohibited in Java
Contains the Object class
The name given to abstract classes in other programming languages, such as C++

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Question 2

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?

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{ 
    void firstMethod(int anIntNum)...

Question 3

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

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Question 4

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

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{ 
    public static void...

Question 5

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?

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Question 6

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

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Question 7

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

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Question 8

Compare and contrast abstract classes and interfaces.

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Question 9

The equals() method returns a boolean value indicating whether two objects are equal. Using the above code, will the two BankAccount objects be equal? Explain why or why not.

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The equals() method returns...

Question 10

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

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{ 
} 
public class...

Question 11

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

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Question 12

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

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Question 13

How is the Object class equals() method implemented?

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Question 14

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

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Question 15

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

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Question 16

What is dynamic method binding and why is it used?

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Question 17

The AnimalReference application shown above contains a generic Animal reference variable into which you can assign concrete Animal objects. Explain how this example uses polymorphism and why it is important.

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The AnimalReference application shown above contains...

Question 18

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.

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{ 
    private String...

Question 19

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.

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