Static and Non-Static Variables in Java

[MyrinNew]

Non-Static Variables

• In Java, variables are used to store data. Based on how memory is allocated and how values are shared, variables can be static or non-static (instance).
• Understanding this difference is important for writing efficient and well-structured programs.

Non-Static (Instance) Variables


A non-static variable is declared inside a class but outside any method, without using the static keyword. Each object of the class gets its own separate copy of the variable.


Key Points

• Created when an object is created
• Each object has a different value
• Stored in heap memory
• Accessed using object reference

Example






class Student {
int marks;
}

public class Main {
public static void main(String[] args) {
Student s1 = new Student();
Student s2 = new Student();

s1.marks = 80;
s2.marks = 90;

System.out.println(s1.marks); // 80
System.out.println(s2.marks); // 90
}
}

• Here, marks is a non-static variable, so each Student object has its own value.

Static Variables

A static variable is declared using the static keyword. It belongs to the class, not to individual objects. Only one copy of a static variable exists, shared by all objects of the class.


Key Points

• Created once when the class is loaded
• Shared among all objects
• Stored in method area
• Accessed using class name (recommended)

Example







public class Employee {
String name;
int salary;
static String company_name ="TCS";

public static void main(String[] args)
{

Employee mukesh = new Employee();
mukesh.name = "Mukesh kumar";
mukesh.salary = 10000;

Employee hari = new Employee();
hari.name = "Hari krishnan";
hari.salary = 20000;
}
}









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