Demonstrate static variables, methods and blocks in Java

The static variable is a class level variable and it is common to all the class objects i.e. a single copy of the static variable is shared among all the class objects.

A static method manipulates the static variables in a class. It belongs to the class instead of the class objects and can be invoked without using a class object.

The static initialization blocks can only initialize the static instance variables. These blocks are only executed once when the class is loaded.

A program that demonstrates this is given as follows:

Example

 Live Demo

public class Demo {
   static int x = 10;
   static int y;
   static void func(int z) {
      System.out.println("x = " + x);
      System.out.println("y = " + y);
      System.out.println("z = " + z);
   }
   static {
      System.out.println("Running static initialization block.");
      y = x + 5;
   }
   public static void main(String args[]) {
      func(8);
   }
}

Output

Running static initialization block.
x = 10
y = 15
z = 8

Now let us understand the above program.

The class Demo contains static variables x and y. The static method func() prints the values of x, y and z. A code snippet which demonstrates this is as follows:

static int x = 10;
static int y;
static void func(int z) {
   System.out.println("x = " + x);
   System.out.println("y = " + y);
   System.out.println("z = " + z);
}

The static initialization block initializes the static variable y. In the main() method, the func() method is called. A code snippet which demonstrates this is as follows:

static {
   System.out.println("Running static initialization block.");
   y = x + 5;
}
public static void main(String args[]) {
   func(8);
}