java: A confusion about calling super method in the child class

Question

The parent class and the child class is as follows.

public abstract class Dialog {

public void render() {
    // do something
    System.out.println(this.getClass());
    Button okButton = createButton();
    // for example, click "ok" button to close a dialog.
    okButton.onClick();
    okButton.render();
}

public Button createButton() {
    System.out.println("I'm a Button");
    return null;
}

}

public class WindowsDialog extends Dialog{

@Override
public Button createButton() {

    // do something
    System.out.println("I'm windows button");
    return new WindowsButton();
}

@Override
public void render() {
    super.render();
    System.out.println("I'm in the child class");
}

public static void main(String[] args) {
    new WindowsDialog().render();
}
}

The execution result is:

class com.pattern.design.behavioral.method.factory.WindowsDialog
I'm windows button
I'm in the child class

I thought the invocation of createButton is I'm a button but it was not.

I want to know why the this.getClass is WindowsDialog and the invocation of 'createButton()' is not I'm a Button.