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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