PreferencesTest.java Source code

Introduction

Here is the source code for PreferencesTest.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.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;
}