Swing JFC Java

/*
   This program is a part of the companion code for Core Java 8th ed.
   (http://horstmann.com/corejava)
   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation, either version 3 of the License, or
   (at your option) any later version.
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   You should have received a copy of the GNU General Public License
   along with this program.  If not, see .
*/
import java.awt.EventQueue;
import java.awt.Font;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.BorderFactory;
import javax.swing.GroupLayout;
import javax.swing.JCheckBox;
import javax.swing.JComboBox;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JScrollPane;
import javax.swing.JTextArea;
import javax.swing.LayoutStyle;
import javax.swing.SwingConstants;
/**
 * @version 1.0 2007-04-27
 * @author Cay Horstmann
 */
public class GroupLayoutTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(new Runnable()
         {
            public void run()
            {
               FontFrame frame = new FontFrame();
               frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               frame.setVisible(true);
            }
         });
   }
}
/**
 * A frame that uses a group layout to arrange font selection components.
 */
class FontFrame extends JFrame
{
   public FontFrame()
   {
      setTitle("GroupLayoutTest");
      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);
      ActionListener listener = new FontAction();
      // construct components
      JLabel faceLabel = new JLabel("Face: ");
      face = new JComboBox(new String[] { "Serif", "SansSerif", "Monospaced", "Dialog",
            "DialogInput" });
      face.addActionListener(listener);
      JLabel sizeLabel = new JLabel("Size: ");
      size = new JComboBox(new String[] { "8", "10", "12", "15", "18", "24", "36", "48" });
      size.addActionListener(listener);
      bold = new JCheckBox("Bold");
      bold.addActionListener(listener);
      italic = new JCheckBox("Italic");
      italic.addActionListener(listener);
      sample = new JTextArea();
      sample.setText("The quick brown fox jumps over the lazy dog");
      sample.setEditable(false);
      sample.setLineWrap(true);
      sample.setBorder(BorderFactory.createEtchedBorder());
      pane = new JScrollPane(sample);
      GroupLayout layout = new GroupLayout(getContentPane());
      setLayout(layout);
      layout.setHorizontalGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGroup(
                  layout.createSequentialGroup().addContainerGap().addGroup(
                        layout.createParallelGroup(GroupLayout.Alignment.LEADING).addGroup(
                              GroupLayout.Alignment.TRAILING,
                              layout.createSequentialGroup().addGroup(
                                    layout.createParallelGroup(GroupLayout.Alignment.TRAILING)
                                          .addComponent(faceLabel).addComponent(sizeLabel))
                                    .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                    .addGroup(
                                          layout.createParallelGroup(
                                                GroupLayout.Alignment.LEADING, false)
                                                .addComponent(size).addComponent(face)))
                              .addComponent(italic).addComponent(bold)).addPreferredGap(
                        LayoutStyle.ComponentPlacement.RELATED).addComponent(pane)
                        .addContainerGap()));
      layout.linkSize(SwingConstants.HORIZONTAL, new java.awt.Component[] { face, size });
      layout.setVerticalGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGroup(
                  layout.createSequentialGroup().addContainerGap().addGroup(
                        layout.createParallelGroup(GroupLayout.Alignment.LEADING).addComponent(
                              pane, GroupLayout.Alignment.TRAILING).addGroup(
                              layout.createSequentialGroup().addGroup(
                                    layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
                                          .addComponent(face).addComponent(faceLabel))
                                    .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                    .addGroup(
                                          layout.createParallelGroup(
                                                GroupLayout.Alignment.BASELINE).addComponent(size)
                                                .addComponent(sizeLabel)).addPreferredGap(
                                          LayoutStyle.ComponentPlacement.RELATED).addComponent(
                                          italic, GroupLayout.DEFAULT_SIZE,
                                          GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                    .addPreferredGap(LayoutStyle.ComponentPlacement.RELATED)
                                    .addComponent(bold, GroupLayout.DEFAULT_SIZE,
                                          GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)))
                        .addContainerGap()));
   }
   public static final int DEFAULT_WIDTH = 300;
   public static final int DEFAULT_HEIGHT = 200;
   private JComboBox face;
   private JComboBox size;
   private JCheckBox bold;
   private JCheckBox italic;
   private JScrollPane pane;
   private JTextArea sample;
   /**
    * An action listener that changes the font of the sample text.
    */
   private class FontAction implements ActionListener
   {
      public void actionPerformed(ActionEvent event)
      {
         String fontFace = (String) face.getSelectedItem();
         int fontStyle = (bold.isSelected() ? Font.BOLD : 0)
               + (italic.isSelected() ? Font.ITALIC : 0);
         int fontSize = Integer.parseInt((String) size.getSelectedItem());
         Font font = new Font(fontFace, fontStyle, fontSize);
         sample.setFont(font);
         sample.repaint();
      }
   }
}