Java Static Keyword - Variables, Methods, Blocks and Nested Classes

⏱️ 8 min read • Beginner Level • Lesson 47

The static keyword in Java is used to create class-level members. A static member belongs to the class, not to a specific object.

Before learning static, you should understand Java class and objects, Java class members, and Java constructors.

What is static in Java?

In Java, static is a non-access modifier. It is used with variables, methods, blocks, and nested classes.

A static member belongs to the class. That means it can be accessed using the class name without creating an object.

Types of Static Members in Java

A Java class can have the following static members:

Static Variable in Java

A variable declared with the static keyword is called a static variable. It is also called a class variable.

Static Variable Example

In this example, x is an instance variable, so every object gets its own copy. But y is static, so it is shared by all objects.

class StaticVariableExample {
    int x;
    static int y;

    void counter() {
        x++;
        y++;

        System.out.println("x: " + x);
        System.out.println("y: " + y);
    }

    public static void main(String[] args) {
        StaticVariableExample obj1 = new StaticVariableExample();
        obj1.counter();

        StaticVariableExample obj2 = new StaticVariableExample();
        obj2.counter();
    }
}

Output:

x: 1
y: 1
x: 1
y: 2

Static Method in Java

A method declared with the static keyword is called a static method. It belongs to the class and can be called using the class name.

Static Method Example

class StaticMethodExample {
    int x = 10;
    static int y = 20;

    static void show() {
        System.out.println("Static method called");
        System.out.println("y: " + y);

        StaticMethodExample obj = new StaticMethodExample();
        System.out.println("x: " + obj.x);
    }

    public static void main(String[] args) {
        StaticMethodExample.show();

        // Static method can also be called directly inside same class
        show();
    }
}

Output:

Static method called
y: 20
x: 10
Static method called
y: 20
x: 10

Static Block in Java

A static block, also called a static initializer block, is used to initialize static data. It executes automatically when the class is loaded.

class StaticBlockExample {
    static {
        System.out.println("Static block executed");
    }

    public static void main(String[] args) {
        System.out.println("Main method executed");
    }
}

Output:

Static block executed
Main method executed

Static Nested Class in Java

A class declared inside another class with the static keyword is called a static nested class.

A static nested class can access static members of the outer class directly. To access non-static members, it needs an object of the outer class.

class Outer {
    static String message = "Hello from static member";

    static class Nested {
        void show() {
            System.out.println(message);
        }
    }

    public static void main(String[] args) {
        Outer.Nested obj = new Outer.Nested();
        obj.show();
    }
}

Output:

Hello from static member

static final Variable in Java

A variable declared with static final is usually used to create constants. It belongs to the class and its value cannot be changed after initialization.

class Circle {
    static final double PI = 3.14159;

    public static void main(String[] args) {
        System.out.println("PI: " + Circle.PI);
    }
}

Output:

PI: 3.14159

Static Members vs Instance Members

When Should We Use static?

Common Mistakes with static

Frequently Asked Questions

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