How to add Jbutton from another class to main class

Question

So am I trying to add JButton from another class into my main class, but I have no idea how to. Do I have to use a certain command or import a package to add the button?

//my first class with JButton
public class ScreenInitial
{
  public ScreenInitial()
  {
    JPanel  panel = new JPanel();
    panel.setLayout(new GridLayout(0, 1));
    JButton newArrival = new JButton("New Arrival");
    panel.add(newArrival);
  }
}



//my main class
public class FurryFriendsAnimalShelter extends JFrame
{ 
  public static void main(String[] args)
  {
    JFrame window = new JFrame("FFAS");
    Toolkit tk = Toolkit.getDefaultToolkit();
    int widthScreen = ((int)tk.getScreenSize().getWidth());
    int lengthScreen = ((int) tk.getScreenSize().getWidth());
    window.setSize(widthScreen,lengthScreen);
    window.getContentPane().setBackground(Color.BLACK);
    window.show(true);
  }
}

Answer 1

The easiest way is to extend some JComponent type and let everything rely on that class.

public class NewClass {

    public static void main(String[] args) {
        JFrame window = new JFrame("Furry Friends Animal Shelter");
        Toolkit tk = Toolkit.getDefaultToolkit();
        int widthScreen = ((int) tk.getScreenSize().getWidth());
        int lengthScreen = ((int) tk.getScreenSize().getWidth());
        window.setSize(widthScreen, lengthScreen);
        window.getContentPane().setBackground(Color.BLACK);
        window.add(new ScreenInitial());
        window.show(true);
    }

    public static class ScreenInitial extends JPanel {

        public ScreenInitial() {
            setLayout(new GridLayout(0, 1));
            JButton newArrival = new JButton("New Arrival");
            add(newArrival);
        }
    }
}