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Part of a self-assessment test designed to help you determine how much you know about the this keyword, static final Variables, and initialization of instance iariables in Java.

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

Answer and Explanation

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

Answer and Explanation

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

Answer and Explanation

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

Questions & Answers

material that allows electric current to pass through
Deng Reply
material which don't allow electric current is called
Deng
insulators
Covenant
how to study physic and understand
Ewa Reply
what is conservative force with examples
Moses
what is work
Fredrick Reply
the transfer of energy by a force that causes an object to be displaced; the product of the component of the force in the direction of the displacement and the magnitude of the displacement
AI-Robot
why is it from light to gravity
Esther Reply
difference between model and theory
Esther
Is the ship moving at a constant velocity?
Kamogelo Reply
The full note of modern physics
aluet Reply
introduction to applications of nuclear physics
aluet Reply
the explanation is not in full details
Moses Reply
I need more explanation or all about kinematics
Moses
yes
zephaniah
I need more explanation or all about nuclear physics
aluet
Show that the equal masses particles emarge from collision at right angle by making explicit used of fact that momentum is a vector quantity
Muhammad Reply
yh
Isaac
A wave is described by the function D(x,t)=(1.6cm) sin[(1.2cm^-1(x+6.8cm/st] what are:a.Amplitude b. wavelength c. wave number d. frequency e. period f. velocity of speed.
Majok Reply
what is frontier of physics
Somto Reply
A body is projected upward at an angle 45° 18minutes with the horizontal with an initial speed of 40km per second. In hoe many seconds will the body reach the ground then how far from the point of projection will it strike. At what angle will the horizontal will strike
Gufraan Reply
Suppose hydrogen and oxygen are diffusing through air. A small amount of each is released simultaneously. How much time passes before the hydrogen is 1.00 s ahead of the oxygen? Such differences in arrival times are used as an analytical tool in gas chromatography.
Ezekiel Reply
please explain
Samuel
what's the definition of physics
Mobolaji Reply
what is physics
Nangun Reply
the science concerned with describing the interactions of energy, matter, space, and time; it is especially interested in what fundamental mechanisms underlie every phenomenon
AI-Robot
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Source:  OpenStax, Object-oriented programming (oop) with java. OpenStax CNX. Jun 29, 2016 Download for free at https://legacy.cnx.org/content/col11441/1.201
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