corejava-keyword: What is static variable?

static variable is also known as class variable. If you declare any variable as static, it is known as static variable. The static variable can be used to refer the common property of all objects (that is not unique for each object) e.g. company name of employees,college name of students etc.

The static variable gets memory only once in class area at the time of class loading. The main advantage of static variable is that It makes your program memory efficient (i.e it saves memory).

****************** Let´s have a look of the following example without static *****************

class Student{
int rollno;
String name;
String college="IIT";
}

Suppose there are 500 students in my college, now all instance data members will get memory each time when object is created. All students have their unique rollno and name so instance data member is good. Here, college refers to the common property of all objects.If we make it static,this field will get memory only once.

++++++++++++++++++++++Note:static property is shared to all objects.+++++++++++++++++

Example of static variable:

class Student{
int rollno;
String name;
static String college ="IIT";

Student(int r,String n){
rollno = r;
name = n;
}
void display (){
System.out.println(rollno+" "+name+" "+college);
}

public static void main(String args[]){
Student s1 = new Student (111,"Aman");
Student s2 = new Student (222,"Suman");
s1.display();
s2.display();
}
}

=============================== Output =================================
111 Aman IIT
222 Suman IIT