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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

A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
Aislinn Reply
cm
tijani
what is titration
John Reply
what is physics
Siyaka Reply
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Jude Reply
Can you compute that for me. Ty
Jude
what is the dimension formula of energy?
David Reply
what is viscosity?
David
what is inorganic
emma Reply
what is chemistry
Youesf Reply
what is inorganic
emma
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
Krampah Reply
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
Sahid Reply
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
Samuel Reply
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Joseph Reply
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
Ryan
what's motion
Maurice Reply
what are the types of wave
Maurice
answer
Magreth
progressive wave
Magreth
hello friend how are you
Muhammad Reply
fine, how about you?
Mohammed
hi
Mujahid
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
yasuo Reply
Who can show me the full solution in this problem?
Reofrir Reply
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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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