Difference between static and instance variables

Difference between static and instance variables

1. Static Variables:

• Belong to the class: Shared among all instances of the class.

• Single copy: Only one copy exists in memory, regardless of how many objects are created.

• Accessed via the class: Can be accessed using the class name (ClassName.variable).

• Use case: For constants or values shared across all objects.

2. Instance Variables:

• Belong to the object: Each object has its own copy.

• Multiple copies: Every object created has its own separate memory space for instance variables.

• Accessed via objects: Requires an object to access.

Example:

class Car {
    static String manufacturer = "Tesla";  // static variable
    String model;  // instance variable

    Car(String model) {
        this.model = model;
    }
}

public class Main {
    public static void main(String[] args) {
        Car car1 = new Car("Model S");
        Car car2 = new Car("Model 3");

        // Static variable (shared among all objects)
        System.out.println(Car.manufacturer);  // Tesla

        // Instance variables (unique to each object)
        System.out.println(car1.model);  // Model S
        System.out.println(car2.model);  // Model 3
    }
}

• Static variables are class-level and shared by all objects.

• Instance variables are object-level, with each object having its own copy.