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Part of a self-assessment test designed to help you determine how much you know about interfaces and polymorphic behavior 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. 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

Answer and Explanation

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

Answer and Explanation

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

Questions & Answers

calculate molarity of NaOH solution when 25.0ml of NaOH titrated with 27.2ml of 0.2m H2SO4
Gasin Reply
what's Thermochemistry
rhoda Reply
the study of the heat energy which is associated with chemical reactions
Kaddija
How was CH4 and o2 was able to produce (Co2)and (H2o
Edafe Reply
explain please
Victory
First twenty elements with their valences
Martine Reply
what is chemistry
asue Reply
what is atom
asue
what is the best way to define periodic table for jamb
Damilola Reply
what is the change of matter from one state to another
Elijah Reply
what is isolation of organic compounds
IKyernum Reply
what is atomic radius
ThankGod Reply
Read Chapter 6, section 5
Dr
Read Chapter 6, section 5
Kareem
Atomic radius is the radius of the atom and is also called the orbital radius
Kareem
atomic radius is the distance between the nucleus of an atom and its valence shell
Amos
Read Chapter 6, section 5
paulino
Bohr's model of the theory atom
Ayom Reply
is there a question?
Dr
when a gas is compressed why it becomes hot?
ATOMIC
It has no oxygen then
Goldyei
read the chapter on thermochemistry...the sections on "PV" work and the First Law of Thermodynamics should help..
Dr
Which element react with water
Mukthar Reply
Mgo
Ibeh
an increase in the pressure of a gas results in the decrease of its
Valentina Reply
definition of the periodic table
Cosmos Reply
What is the lkenes
Da Reply
what were atoms composed of?
Moses 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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