What is static in Java?

The static keyword in Java is used for memory management. It can be applied to:

• Variables (fields)
• Methods
• Blocks
• Nested classes

When a member is declared static, it belongs to the class, rather than to any specific instance (object).

Use Cases of static

Static Variable Example

class Student {
    int rollNo;
    String name;
    static String college = "ABC College";  // Shared by all students

    Student(int r, String n) {
        rollNo = r;
        name = n;
    }

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

public class StaticVarExample {
    public static void main(String[] args) {
        Student s1 = new Student(101, "John");
        Student s2 = new Student(102, "Alice");

        s1.display();  // Output: 101 John ABC College
        s2.display();  // Output: 102 Alice ABC College
    }
}

college is shared among all objects — saved in class memory once.

Static Method Example

class Utility {
    static void greet(String name) {
        System.out.println("Hello, " + name);
    }
}

public class StaticMethodExample {
    public static void main(String[] args) {
        Utility.greet("Shahid");  // No need to create object
    }
}

Static methods can be called using the class name directly.

Static Block Example

class StaticBlockExample {
    static int value;

    // Static block runs once when class is loaded
    static {
        value = 100;
        System.out.println("Static block executed.");
    }

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

Output:

Static block executed.
Value: 100

Static block is used to initialize static variables.

Static Nested Class Example

class Outer {
    static class Inner {
        void show() {
            System.out.println("Inside static nested class.");
        }
    }
}

public class StaticNestedClassExample {
    public static void main(String[] args) {
        Outer.Inner obj = new Outer.Inner();  // No need of Outer class object
        obj.show();
    }
}

Key Rules of static

• A static method cannot access non-static (instance) variables/methods directly.
• this and super keywords cannot be used in static context.
• Static members are loaded at class loading time.

Summary