Static Members in Java

 

🔷 Static Members in Java

✅ What is static in Java?

The static keyword in Java is used for memory management. It makes a member (variable or method) belong to the class rather than an instance of the class.

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📌 Types of Static Members:

1. static variables (class variables)

2. static methods

3. static blocks

4. static nested classes

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✅ 1.1 Static Variable

• Shared among all objects of a class.

• Stored in method area (not heap).

• Initialized only once at class loading time.

🔹 Example:

class Student {
    int rollNo;
    static String college = "ABC College";  // static variable

    Student(int r) {
        rollNo = r;
    }

    void display() {
        System.out.println(rollNo + " - " + college);
    }
}

public class Main {
    public static void main(String[] args) {
        Student s1 = new Student(101);
        Student s2 = new Student(102);
        s1.display();
        s2.display();
    }
}

✅ Output:

101 - ABC College
102 - ABC College

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✅ 1.2 Static Method

• Can be called without creating an object.

• Can only access static data directly.

• Cannot use this or super.

🔹 Example:

class MathUtils {
    static int square(int x) {
        return x * x;
    }
}

public class Main {
    public static void main(String[] args) {
        System.out.println(MathUtils.square(5));  // no object needed
    }
}

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✅ 1.3 Static Block

• Used to initialize static variables.

• Runs once when the class is loaded.

🔹 Example:

class Demo {
    static int x;

    static {
        x = 10;
        System.out.println("Static block initialized.");
    }

    static void show() {
        System.out.println("x = " + x);
    }
}

public class Main {
    public static void main(String[] args) {
        Demo.show();
    }
}