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Part of a self-assessment test designed to help you determine how much you know about relational operators, the increment operator, and control structures 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 .

Given: The use of String concatenation in the argument list of the call to the println method in the program shown in Listing 1 will cause seven items to be displayed on the screen, separated by spaces.

True or False? The program produces the output shown below:

false true false false true true false
Listing 1 . Listing for Question 1.
public class Ap025{ public static void main(String args[]){new Worker().doRelat(); }//end main()}//end class definition class Worker{public void doRelat(){ int a = 1, b = 2, c = 3, d = 2;System.out.println( (a == b) + " " +(b == d) + " " + (b != d) + " " +(c<a) + " " + (b<= d) + " " + (c>d) + " " + (a>= c)); }//end doRelat()}//end class definition

Answer and Explanation

Question 2

What output is produced by the program shown in Listing 2 ?

  • A. Compiler Error
  • B. Runtime Error
  • C. true
  • D. false
Listing 2 . Listing for Question 2.
public class Ap026{ public static void main(String args[]){new Worker().doRelat(); }//end main()}//end class definition class Worker{public void doRelat(){ Dummy x = new Dummy();Dummy y = new Dummy(); System.out.println(x == y);}//end doRelat() }//end class definitionclass Dummy{ int x = 5;double y = 5.5; String z = "A String Object";}//end class Dummy

Answer and Explanation

Question 3

What output is produced by the program shown in Listing 3 ?

  • A. Compiler Error
  • B. Runtime Error
  • C. true
  • D. false
Listing 3 . Listing for Question 3.
public class Ap027{ public static void main(String args[]){new Worker().doRelat(); }//end main()}//end class definition class Worker{public void doRelat(){ Dummy x = new Dummy();Dummy y = new Dummy(); System.out.println(x.equals(y));}//end doRelat() }//end class definitionclass Dummy{ int x = 5;double y = 5.5; String z = "A String Object";}//end class Dummy

Answer and Explanation

Question 4

What output is produced by the program shown in Listing 4 ?

  • A. Compiler Error
  • B. Runtime Error
  • C. true false
  • D. false true
  • E. true true
Listing 4 . Listing for Question 4.
public class Ap028{ public static void main(String args[]){new Worker().doRelat(); }//end main()}//end class definition class Worker{public void doRelat(){ Dummy x = new Dummy();Dummy y = x; System.out.println((x == y) + " " + x.equals(y)); }//end doRelat()}//end class definition class Dummy{int x = 5; double y = 5.5;String z = "A String Object"; }//end class Dummy

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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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