Question

I was helping a friend on his Java homework today, and I guess I didn’t realize there being a difference between plain Java and Java in Android. Quick write up of the program:

public class myClass{

    public static void Main (String[] args){
        doThis();
    }

    public void doThis(){
        System.out.println("Did this");
    }
}

But when running that, I got a complaint that I needed to make the doThis() method to be static. Why is that? When I develop some basic things in Android, I never have to use the static keyword.

Note: This could stem from the fact that I’m intimidated by what static actually means.

Answer 1

Why is that?

Because Main() is static.

If Main() was an instance method, and you had called Main() on an instance of myClass (e.g., new myClass), then doThis() could also be an instance method. Or, if your static Main() created an instance of myClass, it could call doThis() on that instance.

When I develop some basic things in Android, I never have to use the static keyword.

That is because your entry points in Android tend to be instance methods on components (e.g., onCreate() of an Activity.