A frame that restores position and size from user preferences and updates the preferences upon exit : Preference Properties « Development Class « Java






A frame that restores position and size from user preferences and updates the preferences upon exit

  
/*
   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 <http://www.gnu.org/licenses/>.
*/

import java.awt.EventQueue;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.util.prefs.Preferences;

import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JOptionPane;

/**
 * A program to test preference settings. The program remembers the frame position, size, and title.
 * @version 1.02 2007-06-12
 * @author Cay Horstmann
 */
public class PreferencesTest
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(new Runnable()
         {
            public void run()
            {
               PreferencesFrame frame = new PreferencesFrame();
               frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               frame.setVisible(true);
            }
         });
   }
}

/**
 * A frame that restores position and size from user preferences and updates the preferences upon
 * exit.
 */
class PreferencesFrame extends JFrame
{
   public PreferencesFrame()
   {
      // get position, size, title from preferences

      Preferences root = Preferences.userRoot();
      final Preferences node = root.node("/com/horstmann/corejava");
      int left = node.getInt("left", 0);
      int top = node.getInt("top", 0);
      int width = node.getInt("width", DEFAULT_WIDTH);
      int height = node.getInt("height", DEFAULT_HEIGHT);
      setBounds(left, top, width, height);

      // if no title given, ask user

      String title = node.get("title", "");
      if (title.equals("")) title = JOptionPane.showInputDialog("Please supply a frame title:");
      if (title == null) title = "";
      setTitle(title);

      // set up file chooser that shows XML files

      final JFileChooser chooser = new JFileChooser();
      chooser.setCurrentDirectory(new File("."));

      // accept all files ending with .xml
      chooser.setFileFilter(new javax.swing.filechooser.FileFilter()
         {
            public boolean accept(File f)
            {
               return f.getName().toLowerCase().endsWith(".xml") || f.isDirectory();
            }

            public String getDescription()
            {
               return "XML files";
            }
         });

      // set up menus
      JMenuBar menuBar = new JMenuBar();
      setJMenuBar(menuBar);
      JMenu menu = new JMenu("File");
      menuBar.add(menu);

      JMenuItem exportItem = new JMenuItem("Export preferences");
      menu.add(exportItem);
      exportItem.addActionListener(new ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               if (chooser.showSaveDialog(PreferencesFrame.this) == JFileChooser.APPROVE_OPTION)
               {
                  try
                  {
                     OutputStream out = new FileOutputStream(chooser.getSelectedFile());
                     node.exportSubtree(out);
                     out.close();
                  }
                  catch (Exception e)
                  {
                     e.printStackTrace();
                  }
               }
            }
         });

      JMenuItem importItem = new JMenuItem("Import preferences");
      menu.add(importItem);
      importItem.addActionListener(new ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               if (chooser.showOpenDialog(PreferencesFrame.this) == JFileChooser.APPROVE_OPTION)
               {
                  try
                  {
                     InputStream in = new FileInputStream(chooser.getSelectedFile());
                     Preferences.importPreferences(in);
                     in.close();
                  }
                  catch (Exception e)
                  {
                     e.printStackTrace();
                  }
               }
            }
         });

      JMenuItem exitItem = new JMenuItem("Exit");
      menu.add(exitItem);
      exitItem.addActionListener(new ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               node.putInt("left", getX());
               node.putInt("top", getY());
               node.putInt("width", getWidth());
               node.putInt("height", getHeight());
               node.put("title", getTitle());
               System.exit(0);
            }
         });
   }

   public static final int DEFAULT_WIDTH = 300;
   public static final int DEFAULT_HEIGHT = 200;
}

   
    
  








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