import javax.swing.*;
public class FensterIn
{
public void erstelle()
{
JFrame f = new JFrame("Hauptfenster");
f.setDefaultCloseOperation(3);
f.setLocationRelativeTo(null);
f.setSize(500,500);
JDesktopPane desktop = new JDesktopPane();
f.setContentPane(desktop);
JInternalFrame internal=new JInternalFrame("Innen",true,true,true,true);
internal.setSize(200,200);
internal.setVisible(true);
desktop.add(internal);
f.setVisible(true);
}
public static void main(String[] args)
{
FensterIn f = new FensterIn();
f.erstelle();
}
}