Java puzzle 07: Variables in Java

<< 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 

There are different types of variables in Java. Many beginners does not distinguish between them. Here is a new puzzle.

What is the problem in this code?

Java puzzle 7: Variable types in Java

Level: Easy

public class Student
  static boolean isForeigner;

  public static void main(String[] args)
    String name = "Mike";
    int age = 22;
    static char gender; // m = male, f = female
    System.out.print(name + " ");
    System.out.print(age + " ");
    System.out.print(isForeigner + " ");
Author: Sar Maroof

Answer explanation

  1. In this program the class variable isForeigner is not initialized, which is allowed in Java.
  2. Local variables such as name, age and gender in this program must be initialized.
  3. The problem here is the variable gender, which is a local varable and it is not initialized.
  4. You can fix the issue by initializing the variable gender as follows:
    char gender = ‘m’;


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! 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.

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.

Books by Sar Maroof


 Subscribe to Sar Maroof's RSS feeds!
 Mail this page to a friend!
 Bookmark this page!

Leave a Reply

Your email address will not be published. Required fields are marked *