Static method in java

Question

I heard that static methods should use only static variables in java. But, main method is also static, right?

Answer 1

Maybe this piece of code will enlighten you:

public class Main {

    private String instanceField = "Joe";

    private void instanceMethod() {
        System.out.println("Instance name=" + instanceField);
    }

    public static void main(String[] args) {

        // cannot change instance field without an instance
        instanceField = "Indy"; // compilation error

        // cannot call an instance method without an instance
        instanceMethod(); // compilation error

        // create an instance
        Main instance = new Main();

        // change instance field
        instance.instanceField = "Sydney";

        // call instance method
        instance.instanceMethod();  
    }
}

So you cannot access instance members without an instance. Within the context of a static method you don't have a reference to an instance unless you receive or create one.

Hope this helps.