A frame that restores position and size from a properties file and updates the properties upon exit : Preference Properties « Development Class « Java

A frame that restores position and size from a properties file and updates the properties upon exit

A frame that restores position and size from a properties file and updates the properties upon exit
   This program is a part of the companion code for Core Java 8th ed.

   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
   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.WindowAdapter;
import java.awt.event.WindowEvent;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.util.Properties;

import javax.swing.JFrame;
import javax.swing.JOptionPane;

 * A program to test properties. The program remembers the frame position, size, and title.
 * @version 1.00 2007-04-29
 * @author Cay Horstmann
public class PropertiesTest
   public static void main(String[] args)
      EventQueue.invokeLater(new Runnable()
            public void run()
               PropertiesFrame frame = new PropertiesFrame();

 * A frame that restores position and size from a properties file and updates the properties upon
 * exit.
class PropertiesFrame extends JFrame
   public PropertiesFrame()
      // get position, size, title from properties

      String userDir = System.getProperty("user.home");
      File propertiesDir = new File(userDir, ".corejava");
      if (!propertiesDir.exists()) propertiesDir.mkdir();
      propertiesFile = new File(propertiesDir, "program.properties");

      Properties defaultSettings = new Properties();
      defaultSettings.put("left", "0");
      defaultSettings.put("top", "0");
      defaultSettings.put("width", "" + DEFAULT_WIDTH);
      defaultSettings.put("height", "" + DEFAULT_HEIGHT);
      defaultSettings.put("title", "");

      settings = new Properties(defaultSettings);

      if (propertiesFile.exists()) try
         FileInputStream in = new FileInputStream(propertiesFile);
      catch (IOException ex)

      int left = Integer.parseInt(settings.getProperty("left"));
      int top = Integer.parseInt(settings.getProperty("top"));
      int width = Integer.parseInt(settings.getProperty("width"));
      int height = Integer.parseInt(settings.getProperty("height"));
      setBounds(left, top, width, height);

      // if no title given, ask user

      String title = settings.getProperty("title");
      if (title.equals("")) title = JOptionPane.showInputDialog("Please supply a frame title:");
      if (title == null) title = "";

      addWindowListener(new WindowAdapter()
            public void windowClosing(WindowEvent event)
               settings.put("left", "" + getX());
               settings.put("top", "" + getY());
               settings.put("width", "" + getWidth());
               settings.put("height", "" + getHeight());
               settings.put("title", getTitle());
                  FileOutputStream out = new FileOutputStream(propertiesFile);
                  settings.store(out, "Program Properties");
               catch (IOException ex)

   private File propertiesFile;
   private Properties settings;

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


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