Java Static Variable

• Static variable is used to retain its value on every function call.
• Static variable is initialized once.
• Scope of static variable is at program level.
• If no initial value is given to static variable, then its default value is zero.
• Static variable is defined using the keyword 'static'.

Example

class countobject {
         static int i; // default value of i is zero
        countobject ()  
         {
            i++;
         }
        void show()
         {
           System.out.println("Number of objects are " + i);
         }
	public static void main(String args[])
	{
		countobject obj1 = new countobject();
		countobject obj2 = new countobject();
		countobject obj3 = new countobject();  		
		obj3.show();
	}
  }        

Explanation of the program

• Class countobject defines a static variable i . It is of type integer.
• Here, no initial value is given to static variable i . Therefore, default value of i is zero.
• A constructor is defined in which static variable i is incremented whenever an object of the class countobject is created.
• Three objects are created in the example.
• To display value of static variable i . We call show() method.
• Because variable i is defined as static. Therefore, variable i retains its value in multiple calls of the constructor.

Output of the program

Number of objects are 3