seeing if access may be altered

FileSelector.java

package edu.duke;

import java.io.File;
import javax.swing.JFileChooser;
import javax.swing.JOptionPane;
import javax.swing.SwingUtilities;
import javax.swing.filechooser.FileFilter;


/**
 * This utility class creates a thread safe file dialog box for loading and
 * saving files.
 * 
 * @author Duke Software Team
 * 
 *         This software is licensed with an Apache 2 license, see
 *         http://www.apache.org/licenses/LICENSE-2.0 for details.
 */
public class FileSelector {
    // result of selection
    private static File[] ourFiles;
    // BUGBUG: I think this is the right behavior, remembers where user left it last
    public static JFileChooser ourChooser = new JFileChooser();
    static {
        ourChooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
        ourChooser.setCurrentDirectory(new File(System.getProperty("user.dir")));
    }


    /**
     * Pops up a dialog box to select only one file.
     * 
     * @return
     */
    public static File selectFile () {
        // guaranteed to have one element, though it may be null
        return selectFiles(null, false, true)[0];
    }

    /**
     * Pops up a dialog box to select only one file with given extensions.
     */
    public static File selectFile (String[] extensionAccepted) {
        // guaranteed to have one element, though it may be null
        return selectFiles(extensionAccepted, false, true)[0];
    }

    /**
     * Pops up a dialog box to select multiple files.
     */
    public static File[] selectFiles () {
        return selectFiles(null, true, true);
    }

    /**
     * Pops up a dialog box to select multiple files with given extensions.
     * @return
     */
    public static File[] selectFiles (String[] extensionAccepted) {
        return selectFiles(extensionAccepted, true, true);
    }

    /**
     * Pops up a dialog box to save file with any extension.
     */
    public static File saveFile () {
        // guaranteed to have one element, though it may be null
        return selectFiles(null, false, false)[0];
    }

    /**
     * Pops up a dialog box to save file with given extensions.
     */
    public static File saveFile (String[] extensionAccepted) {
        // guaranteed to have one element, though it may be null
        return selectFiles(extensionAccepted, false, false)[0];
    }


    // BUGBUG: one general function, but lots of booleans :( 
    private static File[] selectFiles (String[] extensionAccepted,
                                       final boolean allowMultiple,
                                       final boolean openForRead) {
        ourChooser.setMultiSelectionEnabled(allowMultiple);
        ourChooser.setFileFilter(new ChooserFilter(extensionAccepted));

        try {
            ourFiles = null;
            SwingUtilities.invokeAndWait(new Runnable() {
                @Override
                public void run () {
                    int result = 0;
                    if (openForRead) {
                        result = ourChooser.showOpenDialog(null);
                    }
                    else {
                        result = ourChooser.showSaveDialog(null);
                    }
                    if (result == JFileChooser.CANCEL_OPTION) {
                        ourFiles = new File[] { null };
                    } else {
                        try {
                            if (allowMultiple) {
                                ourFiles = ourChooser.getSelectedFiles();
                            } else {
                                ourFiles = new File[] { ourChooser.getSelectedFile() };
                            }
                        } catch (Exception e) {
                            JOptionPane.showMessageDialog(null, e.toString());
                        }
                    }
                }
            });
            return ourFiles;
        } catch (Exception e) {
            // it is still an exception, just not one required to be handled
            throw new RuntimeException(e);
        }
    }


    // This class implements a filter for image file names.
    static class ChooserFilter extends FileFilter {
        private String myExtensions;

        public ChooserFilter (String[] extensionsAccepted) {
            if (extensionsAccepted != null) {
                myExtensions = String.format("(?i).*\\.(%s)", String.join("|", extensionsAccepted));
            }
        }
        @Override
        public boolean accept (File f) {
            if (myExtensions != null) {
                return f.getName().matches(myExtensions) || f.isDirectory();
            } else {
                return true;
            }
        }
        @Override
        public String getDescription () {
            // BUGBUG: useful?
            return "Files";
        }
    }
}