Java puzzle 15: Objects and methods

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If this program is compiled and run, it writes 2x to the standard output. Write only one statement on line 14. As a result of your statement the program should write 7xy to the standard output. What is that statement?

Java puzzle 15: Objects and methods

Level: Normal

public class MyClass
{
  int i = 2;
  String str = "x";
  
  void change(int i, String str)
  {
    this.i += i;
    this.str += str;
  }
  public static void main(String[] args)
  {
    MyClass mc = new MyClass();
    // add your statement here
    System.out.print(mc.i + mc.str);
  }
}
Author: Sar Maroof

Answer explanation

  1. The program writes 2x to the standard output.
  2. We can change the values of the variable i and the object str by using the method change.
  3. The statement mc.change(5, “y”); increments the value of i by 5. So, i = 2 + 5 = 7.
  4. The parameter y adds y to the object str which contains x already. Therefore, the value of i = 7, and the value of str = “xy”.

The answer is: mc.change(5, “y”);





Sar Maroof is a professional software development teacher, gives master classes and publishes technical articles. He is also an expert software developer and worked for several big as well as small companies and later as a freelancer.

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