Understanding Static and Non-Static Variables in Java

Java is an object-oriented programming language where variables play a crucial role in storing and managing data. Among them, static and non-static (instance) variables are very important concepts every beginner must understand.

What is a Variable in Java?

A variable is a container used to store data values. In Java, variables are mainly categorized based on how they are declared and used.

Two important types are:

• Static variables
• Non-static (instance) variables

Static Variables in Java

A static variable is a variable that is shared among all objects of a class. It belongs to the class rather than any specific object.

Key Features

• Declared using the static keyword
• Only one copy exists for the entire class
• Shared across all objects
• Memory is allocated once when the class is loaded

Example

class Student {
    static String college = "ABC College";
}

public class Main {
    public static void main(String[] args) {
        System.out.println(Student.college);
    }
}

Output

ABC College

Non-Static (Instance) Variables

A non-static variable (also called an instance variable) belongs to an object. Each object has its own copy.

Key Features

• No static keyword used
• Each object has its own value
• Stored in heap memory
• Created when an object is created

Example

class Student {
    String name; 
}

public class Main {
    public static void main(String[] args) {
        Student s1 = new Student(); 
        s1.name = "Harini";

        System.out.println(s1.name); 
    }
}

Output

Harini