Question 1

Consider the following code snippet: public class Employee
{
) . .
Public void setDepartment(String deptName)
{
) . .
}
}
Public class Programmer extends Employee
{
) . .
Public void setProjectName(String projName)
{
) . .
}
Public void setDepartment(String deptName)
{
) . .
}
}
Which of the following statements is NOT correct?

Accepted Answer

A)  The Programmer class can call the setDepartment method of the Employee class. 
B)  The Employee class can call the setProjectName method. 
C)  The Programmer class's setDepartment method overrides the Employee class's setDepartment method. 
D)  The Programmer class can call the setDepartment method of the Programmer class.

Question 2

Consider the following code snippet: public class Motorcycle extends Vehicle
{
) . .
Public Motorcycle(int numberAxles)
{
Super.numberAxles;
}
}
What does this code do?

Accepted Answer

A)  It invokes the constructor of the Vehicle class from within the constructor of the Motorcycle class. 
B)  It invokes the constructor of the Motorcycle class from within the constructor of the Vehicle class. 
C)  It invokes a private method of the Vehicle class from within a method of the Motorcycle class. 
D)  This code will not compile.

Question 3

You are creating a Motorcycle class that is supposed to be a subclass of the Vehicle class. Which of the following class declaration statements will accomplish this?

Accepted Answer

A)  public class Vehicle extends Motorcycle 
B)  public class Motorcycle extends Vehicle 
C)  public class Vehicle inherits Motorcycle 
D)  public class Motorcycle inherits Vehicle

Question 4

To override a superclass method in a subclass, the subclass method ____.

Accepted Answer

A)  Must use a different method name. 
B)  Must use the same method name and the same parameter types. 
C)  Must use a different method name and the same parameter types. 
D)  Must use a different method name and different parameter types.

Question 5

Consider the following code snippet: public class Vehicle
{
Protected int numberAxles;
) . .
}
Data in the numberAxles variable can be accessed by ____.

Accepted Answer

A)  Only by the Vehicle class's methods and by all of its subclasses 
B)  Only by the Vehicle class's methods, by all of its subclasses, and by methods in classes within the same package. 
C)  Only by the Vehicle class's methods. 
D)  By any class.

Question 6

Which of the following is true regarding subclasses?

Accepted Answer

A)  A subclass that inherits methods from its superclass may not override the methods. 
B)  A subclass that inherits instance variables from its superclass may not declare additional instance variables. 
C)  A subclass may inherit methods or instance variables from its superclass but not both. 
D)  A subclass may inherit methods and instance variables from its superclass, and may also implement its own methods and declare its own instance variables.

Question 7

Which of the following statements about abstract methods is true?

Accepted Answer

A)  An abstract method has a name, parameters, and a return type, but no code in the body of the method. 
B)  An abstract method has parameters, a return type, and code in its body, but has no defined name. 
C)  An abstract method has a name, a return type, and code in its body, but has no parameters. 
D)  An abstract method has only a name and a return type, but no parameters or code in its body.

Question 8

Consider the following code snippet: public class Motorcycle extends Vehicle
{
) . .
Public Motorcycle(int numberAxles)
{
Super(numberAxles); //line #1
}
}
If the line marked "//line #1" was missing, which of these statements would be correct?

Accepted Answer

A)  The Motorcycle class constructor would invoke the constructor of the Vehicle class with no parameters. 
B)  The Vehicle class constructor would invoke the constructor of the Motorcycle class with no parameters. 
C)  The Motorcycle class constructor would invoke the constructor of the Vehicle class with a parameter value of 0. 
D)  This code would not compile.

Question 9

Consider the following code snippet: public class Coin
{
Private String name;
) . .
Public boolean equals(Object otherCoin)
{
Return name.equals(otherCoin.name);
}
) . .
}
What is wrong with this code?

Accepted Answer

A)  The return statement should use the == operator instead of the equals method. 
B)  The parameter in the equals method should be declared as Coin otherCoin. 
C)  otherCoin must be cast as a Coin object before using the equals method. 
D)  There is nothing wrong with this code.

Question 10

You are creating a Motorcycle class which is supposed to be a subclass of the Vehicle class. Which of the following class declaration statements will accomplish this?

Accepted Answer

A)  public class Motorcycle extends Vehicle 
B)  public class Motorcycle implements Vehicle 
C)  public class Motorcycle interfaces Vehicle 
D)  public class Motorcycle inherits Vehicle

Question 11

Which of the following statements about comparing objects is correct?

Accepted Answer

A)  The equals method is used to compare whether two references are to the same object. 
B)  The equals method is used to compare whether two objects have the same contents. 
C)  The == operator is used to compare whether two objects have the same contents. 
D)  The equals method and the == operator perform the same actions.

Question 12

Consider the following code snippet of a function object public interface Measurer
{
Double measure(______ anObject);
}
Complete this code to allow the interface to handle all classes?

Accepted Answer

A)  Class 
B)  Object 
C)  Any 
D)  Void

Question 13

When declared as protected, data in an object can be accessed by ____.

Accepted Answer

A)  Only by that class's methods and by all of its subclasses 
B)  Only by that class's methods, by all of its subclasses, and by methods in classes within the same package. 
C)  Only by that class's methods. 
D)  By any class.

Question 14

All hamsters are rodents and all rodents are mammals. What hierarchy best captures this information?

Accepted Answer

A)  Hamster is a superclass of Rodent and Rodent is a superclass of Mammal 
B)  Mammal is a superclass of Rodent and Rodent is a superclass of Hamster 
C)  Mammal is a superclass of Rodent and Hamster 
D)  Hamster is a superclass of Rodent and Mammal

Question 15

Consider the classes shown below: public class Parent
{
Public void doSomething(){/* Implementation not shown */}
}
Public class Child extends Parent
{
Public void doAnotherThing(){/* Implementation not shown */}
}
Which lines in the following code will compile without error?
Parent kid = new Child();
Kid)doSomething(); // line 1
Kid)doAnotherThing(); // line 2

Accepted Answer

A)  Line 1 only 
B)  Line 2 only 
C)  Lines 1 and 2 
D)  Neither line will compile without error

Question 16

Consider the following code snippet: public abstract class Employee
{
Public abstract void setSalary();
) . .
}
You wish to create a concrete subclass named Programmer. Which of the following is the correct way to declare this subclass?

Accepted Answer

A)  public class Programmer implements Employee
{
Public void setSalary() { . . . }
} 
B)  public class Programmer extends Employee
{
Void setSalary() { . . . }
} 
C)  public class Programmer implements Employee
{
Void setSalary() { . . . }
} 
D)  public class Programmer extends Employee
{
Public void setSalary() { . . . }
}

Question 17

A class that represents a more specific entity in an inheritance hierarchy is called a/an ____.

Accepted Answer

A)  Default class 
B)  Superclass 
C)  Subclass. 
D)  Inheritance class.

Question 18

Consider the classes shown below: public class Parent
{
Public void doSomething() // method 1
{ /* Implementation not shown */ }
}
Public class Child extends Parent {
Public void doSomething(int n) // method 2
{ /* Implementation not shown */ }
Public void doSomething() // method 3
{ /* Implementation not shown */ }
}
If the variable kid is defined below, which version of the doSomething method can be called on the variable kid?
Parent kid = new Child();

Accepted Answer

A)  Method 1 only 
B)  Methods 2 and 3 only 
C)  Methods 1 and 2 only 
D)  Methods 1, 2, and 3

Question 19

Consider the classes shown below: public class Parent
{
Public void doSomething(){/* Implementation not shown */}
}
Public class Child extends Parent
{
Public void doAnotherThing(){/* Implementation not shown */}
}
Which lines in the following code will compile without error?
Child kid = new Child();
Kid)doSomething(); // line 1
Kid)doAnotherThing(); // line 2

Accepted Answer

A)  Line 1 only 
B)  Line 2 only 
C)  Lines 1 and 2 
D)  Neither line will compile without error

Question 20

Consider the following code snippet: public class Vehicle
{
) . .
Public void setVehicleClass(double numberAxles)
{
) . .
}
}
Public class Motorcycle extends Vehicle
{
) . .
Public void setVehicleClass(double numberAxles)
{
) . .
}
}
Which of the following statements is correct? (I changed the wording below, because methods override methods. . .classes don't override methods)

Accepted Answer

A)  The Motorcycle class's setVehicleClass method overrides the Vehicle class's setVehicleClass method. 
B)  The Vehicle class's setVehicleClass method overrides the Motorcycle class's setVehicleClass method. 
C)  The Motorcycle class's setVehicleClass method overloads the Vehicle class's setVehicleClass method. 
D)  The Vehicle class's setVehicleClass method overloads the Motorcycle class's setVehicleClass method.

Exam 9: Inheritance

Consider the following code snippet: public class Motorcycle extends Vehicle { ) . . Public Motorcycle(int numberAxles) { Super.numberAxles; } } What does this code do?

You are creating a Motorcycle class that is supposed to be a subclass of the Vehicle class. Which of the following class declaration statements will accomplish this?

To override a superclass method in a subclass, the subclass method ____.

Consider the following code snippet: public class Vehicle { Protected int numberAxles; ) . . } Data in the numberAxles variable can be accessed by ____.

Which of the following is true regarding subclasses?

Which of the following statements about abstract methods is true?

Consider the following code snippet: public class Motorcycle extends Vehicle { ) . . Public Motorcycle(int numberAxles) { Super(numberAxles) ; //line #1 } } If the line marked "//line #1" was missing, which of these statements would be correct?

Consider the following code snippet: public class Coin { Private String name; ) . . Public boolean equals(Object otherCoin) { Return name.equals(otherCoin.name) ; } ) . . } What is wrong with this code?

You are creating a Motorcycle class which is supposed to be a subclass of the Vehicle class. Which of the following class declaration statements will accomplish this?

Which of the following statements about comparing objects is correct?

Consider the following code snippet of a function object public interface Measurer { Double measure(______ anObject) ; } Complete this code to allow the interface to handle all classes?

When declared as protected, data in an object can be accessed by ____.

All hamsters are rodents and all rodents are mammals. What hierarchy best captures this information?

Consider the following code snippet: public abstract class Employee { Public abstract void setSalary() ; ) . . } You wish to create a concrete subclass named Programmer. Which of the following is the correct way to declare this subclass?

A class that represents a more specific entity in an inheritance hierarchy is called a/an ____.