Table of contents
Preface
This module is part of a self-assessment test designed to help you determine how much you know about object-orientedprogramming using Java.
The test consists of a series of questions with answers and explanations of the answers.
The questions and the answers are connected by hyperlinks to make it easy for you to navigate from the question to the answer and back.
I recommend that you open another copy of this document in a separate browser window and use the links to under Listings to easily find and view the listings while you are reading about them.
Questions
Question 1 .
What output is produced by the program shown in Listing 1 ?
- A. Compiler Error
- B. Runtime Error
- C. Base A-intfcMethod
- D. None of the above.
| Listing 1 . Listing for Question 1. |
|---|
public class Ap131{
public static void main(String args[]){new Worker().doIt();
}//end main()}//end class Ap131
class Worker{void doIt(){
Base myVar1 = new Base();myVar1.inherMethod();
X myVar2 = new A();myVar2.intfcMethod();
System.out.println("");}//end doIt()
}// end class Workerclass Base{
public void inherMethod(){System.out.print("Base ");
}//end inherMethod()}//end class Base
class A extends Base{public void inherMethod(){
System.out.print(" A-inherMethod ");
}//end inherMethod()public void intfcMethod(){System.out.print("A-intfcMethod ");
}//end intfcMethod()}//end class A
interface X{public void intfcMethod();
}//end X |
Question 2
What output is produced by the program shown in Listing 2 ?
- A. Compiler Error
- B. Runtime Error
- C. A-inherMethod A-intfcMethod
- D. None of the above.
| Listing 2 . Listing for Question 2. |
|---|
public class Ap132{
public static void main(String args[]){new Worker().doIt();
}//end main()}//end class Ap132
class Worker{void doIt(){
Base myVar1 = new Base();myVar1.inherMethod();
Base myVar2 = new A();myVar2.intfcMethod();
System.out.println("");}//end doIt()
}// end class Workerclass Base{
public voidinherMethod(){
System.out.print("Base ");}//end inherMethod()
}//end class Baseclass A extends Base implements X{
public void inherMethod(){System.out.print(
" A-inherMethod ");}//end inherMethod()public void intfcMethod(){
System.out.print("A-intfcMethod ");}//end intfcMethod()
}//end class Ainterface X{
public void intfcMethod();}//end X |
Question 3
What output is produced by the program shown in Listing 3 ?
- A. Compiler Error
- B. Runtime Error
- C. Base A-intfcMethod
- D. None of the above.
| Listing 3 . Listing for Question 3. |
|---|
public class Ap133{
public static void main(String args[]){new Worker().doIt();
}//end main()}//end class Ap133
class Worker{void doIt(){
Base myVar1 = new Base();myVar1.inherMethod();
A myVar2 = new A();myVar2.intfcMethod();
System.out.println("");}//end doIt()
}// end class Workerclass Base{
public void inherMethod(){System.out.print("Base ");
}//end inherMethod()}//end class Base
class A extends Base implements X{public void inherMethod(){
System.out.print(" A-inherMethod ");
}//end inherMethod()public void intfcMethod(){System.out.print("A-intfcMethod ");
}//end intfcMethod()}//end class A
interface X{public void intfcMethod();
}//end X |