Java puzzle 17: Classes and objects

<<	Java Puzzles Green = Easy, Blue = Normal, Red = Hard 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 By title	>>

The output of this code is 2y2. Add only one statement at line 20. As a result of your statement, the output of the program becomes 9×5.
What is that statement?

Java puzzle 17: Classes and objects

Level: Hard

public class MyClass
{
  int i = 2;
  String str;
  
  MyClass(String str)
  {
    this.str = str;
  }
  int myMethod(int i, String str)
  {
    this.i = i += 2;
    this.str = str;
    return(i + 4);
  }
  public static void main(String[] args)
  {
    MyClass mc = new MyClass("x");
    MyClass mc2 = new MyClass("y");
    // add your statement here!
    System.out.print(mc.i);
    System.out.print(mc2.str);
    System.out.print(mc2.i);
  }
}

Author: Sar Maroof

Answer explanation

The statement should reassign the variable i of the object mc.
The same statement should reassign the value of the variable i and the object str of the object mc2.
To do that we need to use the method myMethod. We can use the method to reassign the value of the variable i and the value of the object str of the object mc2.
To reassign the value of the variable i of the object mc, we can simply reassign its value to the vlaue that the method myMethod returns as follows.
mc.i = mc2.myMethod(3, “x”);

If you found this difficult, you might consider reading my book Java quizmaster for beginners. It is easy to understand, organized to learn Java in 17 days and it guides you to master Java code by solving 105 quizzes and 117 assignments. This book explains each chapter properly before starting with exercises and assignments. It is available on Amazon. See inside the book here!

Please, leave your questions, feedback and suggestions in the comments below!
SarMaroof.com offers a practical method to learn and improve your Java skills. It avoids unnecessary long boring theoretical explanations, but it uses many exercises and quizzes.

Suggested Articles

Sar Maroof is graduated from HBO Amsterdam "higher professional education". He is a professional computer programming teacher, gives master classes and publishes technical articles. His experience with developing software started from 2001 and he has worked as a software developer for several big as well as small companies and later as a freelancer. He is the author of Java quizmaster and Build a Java application in 7 days.