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. 33
- D. None of the above
| Listing 1 . Listing for Question 1. |
|---|
public class Ap110{
public static void main(String args[]){new Worker().doThis();
}//end main()}//end class Ap110
class Worker{private int data = 33;public void doThis(){
new Helper().helpMe(this);}//end area()public String getData(){
return data;}//end getData()
}// end class Workerclass Helper{
public void helpMe(Worker param){System.out.println(
param.getData());}//end helpMe()
}//end class Helper |
Question 2
What output is produced by the program shown in Listing 2 ?
- A. Compiler Error
- B. Runtime Error
- C. 33
- D. None of the above.
| Listing 2 . Listing for Question 2. |
|---|
public class Ap111{
public static void main(String args[]){new Worker().doThis();
}//end main()}//end class Ap111
class Worker{private int data = 33;public void doThis(){
new Helper().helpMe(this);}//end area()public String getData(){
return "" + data;}//end getData()
}// end class Workerclass Helper{
public void helpMe(Worker param){System.out.println(
param.getData());}//end helpMe()}//end class Helper |
Question 3
What output is produced by the program shown in Listing 3 ?
- A. Compiler Error
- B. Runtime Error
- C. 11
- D. 22
- E. 33
- F. 44
- G. None of the above.
| Listing 3 . Listing for Question 3. |
|---|
public class Ap112{
public static void main(String args[]){Worker obj1 = new Worker(11);
Worker obj2 = new Worker(22);Worker obj3 = new Worker(33);
Worker obj4 = new Worker(44);obj2.doThis();
}//end main()}//end class Ap112
class Worker{private int data;public Worker(int data){
this.data = data;}//end constructorpublic void doThis(){
System.out.println(this);}//end area()public String toString(){
return "" + data;}//end toString()
}// end class Worker |
Question 4
What output is produced by the program shown in Listing 4 ?
Note that 6.283185307179586 is a correct numeric value.
- A. Compiler Error
- B. Runtime Error
- C. 6.283185307179586
- D. None of the above.
| Listing 4 . Listing for Question 4. |
|---|
public class Ap113{
public static void main(String args[]){System.out.println(
new Worker().twoPI);}//end main()
}//end class Ap113class Worker{
public static final double twoPI;public Worker(){twoPI = 2 * Math.PI;
}//end constructor}// end class Worker |