Java puzzle 02: Conditional statements

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Here is the second simple Java puzzle

If this simple program is compiled and run, it writes the letter “c” to the standard output.
By adding one statement to the line 9, the program writes “ab” to the standard output.
What is that statement?

Java puzzle 2: Conditional statements

Level: Normal

public class MyClass
{
  static int x = 4;
  static int y = 7;
  static int z = 6;

  public static void main(String[] args)
  {
    // add your statement here!
    if (x > y)
    {
      System.out.print("a");
      if (z > y * x && y > 0)
      {
        System.out.print("b");
      }
    }
    else
    {
      System.out.print("c");
    }
  }
}
Author: Sar Maroof

Answer explanation

  1. For the program to write the letter “a” to the standard output, the conditional statement if(x > y) must return true. We can do that either by incrementing the value of x or decrementing the value of y. ┬áBy incrementing the value of x, the second conditional statement if( z > y * x) will return false. Therefore, we better decrement the value of y.
  2. If we decrement the value of y by 6, the conditional statement if(z > y * x) will return true, because z = 6 and y * x = 1 * 4 = 4 and that is smaller than 6.
  3. If we decrement the value of y by 7 or more, the conditional statement if(y > 0) will return false. That is the reason that y should be greater than 0 otherwise the letter b wouldn’t be written to the standard output..

 

public class MyClass
{
  static int x = 4;
  static int y = 7;
  static int z = 6;

  public static void main(String[] args)
  {
    y -= 6; // or y = 1;
    if (x > y)
    {
      System.out.print("a");
      if (z > y * x && y > 0)
      {
        System.out.print("b");
      }
    }
    else
    {
      System.out.print("c");
    }
  }
}

 

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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.

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