Java puzzle 07: Variables in Java

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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’;


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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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