Variables in Java

A variable in Java is a named location in memory that holds a value. Variables are used to store data that can be used throughout a program.

There are three main types of variables in Java:

• Local variables: These variables are declared within a method, constructor, or block of code. They are only accessible within the scope in which they are defined.
• Instance variables: These variables are declared within a class but outside any method, constructor, or block of code. They are associated with individual instances (objects) of the class.
• Static variables: These variables are declared with the static keyword within a class but outside any method, constructor, or block of code. They are associated with the class itself rather than with instances of the class.

Example of local variable

public class LocalVariableExample {
   public static void main(String[] args) {
      int age; // local variable
      age = 25;
      System.out.println("My age is: " + age);
   }
}

Output;

My age is: 25

Example of instance variable

public class InstanceVariableExample {
   // instance variable
   String name;

   public static void main(String[] args) {
      InstanceVariableExample obj = new InstanceVariableExample();
      System.out.println("My name is: " + obj.name);
   }
}

Output:

My name is: null

Example of static variable

public class StaticVariableExample {
   // static variable
   static int count = 0;

   public static void main(String[] args) {
      StaticVariableExample obj1 = new StaticVariableExample();
      obj1.count++;
      StaticVariableExample obj2 = new StaticVariableExample();
      obj2.count++;
      StaticVariableExample obj3 = new StaticVariableExample();
      obj3.count++;
      System.out.println("Total objects created: " + count);
   }
}

Output:

Total objects created: 3

Can you answer why the output is 3?

I would love to hear your answer in the comment section below.

Thank you

Frequently Asked Questions