Static variables in Java

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Introduction

Static variables hold a value shared by all objects of a class. They help save memory and keep common data in one place.

When you want to count how many objects of a class have been created.

When you need a common setting or value shared by all objects, like a company name.

When you want to share a constant value across all instances.

When you want to keep track of a shared resource or status.

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Syntax

Java

class ClassName {
    static DataType variableName;
}

Static variables belong to the class, not to any single object.

You can access static variables using the class name, like ClassName.variableName.

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Examples

line_end_arrow_notchThis declares a static variable numberOfCars shared by all Car objects.

Java

class Car {
    static int numberOfCars;
}

line_end_arrow_notchAccessing and setting the static variable using the class name.

Java

Car.numberOfCars = 5;

line_end_arrow_notchA static variable holding a company name shared by all Example objects.

Java

class Example {
    static String company = "TechCorp";
}

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Sample Program

This program creates three Counter objects. Each time a Counter is made, the static count variable increases by 1. The showCount method prints the total count shared by all objects.

Java

class Counter {
    static int count = 0;

    Counter() {
        count++;
    }

    static void showCount() {
        System.out.println("Count: " + count);
    }
}

public class Main {
    public static void main(String[] args) {
        Counter c1 = new Counter();
        Counter c2 = new Counter();
        Counter c3 = new Counter();

        Counter.showCount();
    }
}

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Important Notes

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Static variables keep their value as long as the program runs.

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They are initialized only once when the class is loaded.

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Use static variables carefully to avoid unwanted shared changes.

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Summary

Static variables belong to the class, not individual objects.

They share the same value across all objects of that class.

Useful for counting objects or storing common data.