PropertiesTest.java Source code

Introduction

Here is the source code for PropertiesTest.java

Source

/*
   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.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();
                frame.setVisible(true);
            }
        });
    }
}

/**
 * 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);
                settings.load(in);
            } catch (IOException ex) {
                ex.printStackTrace();
            }

        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 = "";
        setTitle(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());
                try {
                    FileOutputStream out = new FileOutputStream(propertiesFile);
                    settings.store(out, "Program Properties");
                } catch (IOException ex) {
                    ex.printStackTrace();
                }
                System.exit(0);
            }
        });
    }

    private File propertiesFile;
    private Properties settings;

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