BoxLayout zeigt nichts

[Robbiani]

Cioa Zäme

Kann mir Jemand sagen warum der Panel mit BoxLayout nicht gezeigt wird?

/*
 * Java class source file
 * Copyright© : Haag-Streit Diagnostics
 * Created on : 21.06.2016 by robbiar
 *
 * Revision of last commit : $Rev$
 * Author of last commit : $Author$
 * Date of last commit : $Date$
 * =============================================================================
 * =
 */

package swing_eins;

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyListener;
import java.util.EventObject;

import javax.swing.BorderFactory;
import javax.swing.BoxLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
import javax.swing.UIManager;
import javax.swing.UnsupportedLookAndFeelException;

/**
 *
 * @author robbiar
 */
public class win_start
                       extends JFrame
                       implements ActionListener {

  private static final KeyListener keyListener = null;
  private final JTextField         edt_res;

  public static void main(final String[] args) {
    // TODO Auto-generated method stub
    final win_start fenster = new win_start();
    fenster.setSize(300, 300);
    fenster.setLocation(200, 200);
    fenster.setName("programm");
    fenster.pack();
    fenster.setVisible(true);
  }

  public win_start() {
    super("das programm");

    // Resultat anzeigen
    final JPanel pn_text = new JPanel();
    final JLabel lbl_name = new JLabel("Resultat");
    pn_text.add(lbl_name);
    edt_res = new JTextField(20);
    edt_res.setToolTipText("Resultat der Berechnung");
    edt_res.addFocusListener(null);
    edt_res.addKeyListener(keyListener);
    pn_text.add(edt_res);
    pn_text.setBorder(BorderFactory.createEtchedBorder());
    getContentPane().add(pn_text, BorderLayout.NORTH);

    // Buttons aufbauen
    final JPanel pn_buttons = new JPanel();
    final JPanel pn_eins = new JPanel();
    final JPanel pn_zwei = new JPanel();
    final JPanel pn_drei = new JPanel();
    final JPanel pn_vier = new JPanel();
    final JButton btn_nul = new JButton("0");
    // btn_nul.setLayout(null);
    // btn_nul.setBounds(1, 500, 60, 20);
    btn_nul.setBackground(Color.yellow);
    btn_nul.addActionListener(this);
    pn_eins.add(btn_nul);
    final JButton btn_eins = new JButton("1");
    btn_eins.addActionListener(this);
    // btn_eins.setLayout(null);
    // btn_eins.setBounds(1, 550, 60, 20);
    pn_eins.add(btn_eins);
    final JButton btn_zwei = new JButton("2");
    // btn_zwei.setLayout(null);
    btn_zwei.addActionListener(this);
    pn_eins.add(btn_zwei);
    final JButton btn_drei = new JButton("3");
    // btn_drei.setLayout(null);
    btn_drei.addActionListener(this);
    pn_zwei.add(btn_drei);
    final JButton btn_vier = new JButton("4");
    // btn_vier.setLayout(null);
    btn_vier.addActionListener(this);
    pn_zwei.add(btn_vier);
    final JButton btn_fuenf = new JButton("5");
    // btn_fuenf.setLayout(null);
    btn_fuenf.addActionListener(this);
    pn_zwei.add(btn_fuenf);
    final JButton btn_sechs = new JButton("6");
    // btn_sechs.setLayout(null);
    btn_sechs.addActionListener(this);
    pn_zwei.add(btn_sechs);
    final JButton btn_sieben = new JButton("7");
    // btn_sieben.setLayout(null);
    btn_sieben.addActionListener(this);
    pn_drei.add(btn_sieben);
    final JButton btn_acht = new JButton("8");
    // btn_acht.setLayout(null);
    btn_acht.addActionListener(this);
    pn_drei.add(btn_acht);
    final JButton btn_neun = new JButton("9");
    // btn_neun.setLayout(null);
    btn_neun.addActionListener(this);
    pn_drei.add(btn_neun);
    pn_buttons.setBorder(BorderFactory.createEtchedBorder());
    getContentPane().add(pn_buttons, BorderLayout.SOUTH);
    // edt_res.setText("eingabe");
    pn_eins.setLayout(new BoxLayout(pn_eins, BoxLayout.X_AXIS));
    pn_eins.setBackground(Color.green);
    pn_eins.setToolTipText("das einser Ort");
    getContentPane().add(pn_eins);
    getContentPane().add(pn_zwei, BoxLayout.X_AXIS);
    getContentPane().add(pn_drei, BoxLayout.X_AXIS);
    getContentPane().add(pn_vier, BoxLayout.X_AXIS);
  }

  @Override
  public void actionPerformed(final ActionEvent event) {
    final String cmd = event.getActionCommand();
    final Object was = event.getSource();
    try {
      String name = was.toString();
      final int pos = name.indexOf("[");
      name = name.substring(0, pos);
      if (name.equals("javax.swing.JTextField")) {
        // JTextField neu <? extends Object> = was.getClass();
        ((JTextField) was).setText("ereignis");
      }
      if (name.equals("javax.swing.JButton")) {
        String text = edt_res.getText();
        text += cmd;
        edt_res.setText(text);
      }
      // PLAF-Klasse auswählen
      String plaf = "unknown";
      plaf = cmd;
      // LAF umschalten
      UIManager.setLookAndFeel(plaf);
      SwingUtilities.updateComponentTreeUI(this);
    } catch (final UnsupportedLookAndFeelException e) {
      System.err.println(e.toString());
    } catch (final ClassNotFoundException e) {
      System.err.println(e.toString());
    } catch (final InstantiationException e) {
      System.err.println(e.toString());
    } catch (final IllegalAccessException e) {
      System.err.println(e.toString());
    }
  }

  public void actFocusListener(final KeyListener event) {
    final Object was = ((EventObject) event).getSource();
    String name = was.toString();
    final int pos = name.indexOf("[");
    name = name.substring(0, pos);
    if (was.equals("javax.swing.JTextField")) {
      // JTextField neu <? extends Object> = was.getClass();
      ((JTextField) was).setText("focus!");
    }
  }

}

Danke für eure Hilfe.

Gruss Renato