Java puzzle 13: Invoking methods

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In this Java puzzle the method myMethod is invoked, which returns an integer variable. Two integer parameters are passed to the method.

Java puzzle 13: Invoking a method

Level: Easy

What is the output of this program and why?

public class MyClass
  int i = 2;
  int i2;
  public int myMethod(int i, int i2)
    return i + this.i2;
  public static void main(String[] args)
    MyClass mc = new MyClass();
    System.out.print(mc.myMethod(3, 5));
Author: Sar Maroof

Answer explanation

  1. The parameters 3 and 5 are passed to the method myMethod.
  2. The statement return i + this.i2 returns the value of the
    parameter i plus the value of the instance variable i2. Remember that the keyword this here refers to the instance variable
    not the parameter that passed to the method.
  3. The value of the parameter i is 3 and the value of the instance variable i2 is 0, because it is not initialized.
    Therefore the program writes 3 + 0 = 3 to the standard output.

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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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