import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class Hauptfenster extends JFrame implements ActionListener {
private static final long serialVersionUID = 1L;
public Hauptfenster() {
JPanel dasJPanel = new JPanel();
this.setLayout(new BorderLayout());
this.getContentPane().add(dasJPanel, BorderLayout.NORTH);
JButton btn = new JButton("Klick");
btn.addActionListener(this);
dasJPanel.add(btn);
this.setPreferredSize(new Dimension(400, 400));
this.pack();
this.setVisible(true);
this.setDefaultCloseOperation(EXIT_ON_CLOSE);
}
@Override
public void actionPerformed(ActionEvent e) {
new meineAndereKlasse();
}
}
class Hauptprogramm {
public static void main(String[] args) {
new Hauptfenster();
}
}
class meineAndereKlasse {
public meineAndereKlasse() {
System.out.println("Heureka!");
}
}