Bringing JFileChooser on top of all windows

Question

I seem to have a problem with my very simple implementation of a file chooser dialogue that requires me to minimize Netbeans each time in order to get to it, and it gets pretty frustrating specially now with testing.

I have seen a few solutions online including SO yet none seem to do the trick, while some other seem very lengthy and complicated for my current level.

private void fileSearch() {

    JFileChooser fileSelect = new JFileChooser();
    int returnVal = fileSelect.showOpenDialog(null);
    String pathToFile;

    if (returnVal == JFileChooser.APPROVE_OPTION) {
        File file = fileSelect.getSelectedFile();
        pathToFile = file.getAbsolutePath();
        try {
            P.binaryFileToHexString(pathToFile);
        } catch (Exception e) {
            System.out.print("Oops! there was an error there..." + e);
        }
        System.out.println("\nYou chose to open this file: " + file.getName());
    }
}

Some of my try's include using;

.requestFocus();
.requestFocusInWindow();
.setVisible();

Is there a particular attribute/method I can set in order to solve the problem?

Answer 1

You wrote (in your comment):

Actually no, that's the only method in the whole program that makes use of a UI the rest still is pure console.

In other words, you want to add GUI components to a console application and your problem is that the JFileChooser does not become the active window, i.e. the window that has the keyboard focus.

As stated in the other answer, the problem is that you are setting the parent of the JFileChooser [open] dialog to null.

The below code creates a minimal JFrame that serves as the JFileChooser dialog parent and also serves as a top-level container. In the below code, the user is asked – via the console – if [s]he wants to select a file. If the answer is Y, the JFileChooser dialog is displayed. Once that dialog is closed, the user is again asked whether [s]he wants to select a file. Hence a console application with a GUI component which, I understand, is what you are trying to achieve.

(Notes after the code.)

import java.io.File;
import java.util.Scanner;

import javax.swing.JFileChooser;
import javax.swing.JFrame;

public class SlctFile {

    private static void fileSearch() {
        JFrame frame = new JFrame();
        frame.setAlwaysOnTop(true);
        frame.setVisible(true);
        JFileChooser fileSelect = new JFileChooser();
        int returnVal = fileSelect.showOpenDialog(frame);
        String pathToFile;

        if (returnVal == JFileChooser.APPROVE_OPTION) {
            File file = fileSelect.getSelectedFile();
            pathToFile = file.getAbsolutePath();
            try {
                P.binaryFileToHexString(pathToFile);
            }
            catch (Exception e) {
                System.out.print("Oops! there was an error there..." + e);
            }
            System.out.println("\nYou chose to open this file: " + file.getName());
        }
        frame.dispose();
    }

    public static void main(String[] args) {
        String answer;
        Scanner stdin = new Scanner(System.in);
        do {
            System.out.print("Select file? ");
            answer = stdin.nextLine();
            if ("Y".equalsIgnoreCase(answer)) {
                fileSearch();
            }
        } while ("Y".equalsIgnoreCase(answer));
        System.exit(0);
    }
}

• Method setAlwaysOnTop ensures that the JFrame will become the active window.
• As soon as the JFrame is displayed, the JFileChooser is immediately displayed.
• Calling method exit is required since displaying the JFrame starts up the Event Dispatch Thread (EDT). When the main thread terminates, the EDT does not so calling method exit ensures termination of the JVM.

Answer 2

The API for showOpenDialog() refers to showDialog(), which says, "If the parent is null, then the dialog depends on no visible window, and it's placed in a look-and-feel-dependent position such as the center of the screen."

The example below positions the chooser in the center of the screen on my L&F. You might see how it compares to yours.

package gui;

import java.awt.BorderLayout;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JFileChooser;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JPanel;
import javax.swing.JPopupMenu;
import javax.swing.JScrollPane;
import javax.swing.KeyStroke;

/**
 * @see http://stackoverflow.com/questions/8507521
 * @see http://stackoverflow.com/questions/5129294
 */
public class ImageApp extends JPanel {

    private static final int MASK =
        Toolkit.getDefaultToolkit().getMenuShortcutKeyMask();
    private JFileChooser chooser = new JFileChooser();
    private Action openAction = new ImageOpenAction("Open");
    private Action clearAction = new ClearAction("Clear");
    private JPopupMenu popup = new JPopupMenu();
    private BufferedImage image;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {

            @Override
            public void run() {
                new ImageApp().create();
            }
        });
    }

    public void create() {
        JFrame f = new JFrame();
        f.setTitle("Title");
        f.add(new JScrollPane(this), BorderLayout.CENTER);
        JMenuBar menuBar = new JMenuBar();
        JMenu menu = new JMenu("File");
        menu.setMnemonic('F');
        menu.add(new JMenuItem(openAction));
        menu.add(new JMenuItem(clearAction));
        menuBar.add(menu);
        f.setJMenuBar(menuBar);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.pack();
        f.setSize(new Dimension(640, 480));
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public ImageApp() {
        this.setComponentPopupMenu(popup);
        popup.add("Popup Menu");
        popup.add(new JMenuItem(openAction));
        popup.add(new JMenuItem(clearAction));
    }

    @Override
    public Dimension getPreferredSize() {
        if (image == null) {
            return new Dimension();
        } else {
            return new Dimension(image.getWidth(), image.getHeight());
        }
    }

    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        g.drawImage(image, 0, 0, null);
    }

    private class ClearAction extends AbstractAction {

        public ClearAction(String name) {
            super(name);
            this.putValue(Action.MNEMONIC_KEY, KeyEvent.VK_C);
            this.putValue(Action.ACCELERATOR_KEY,
                KeyStroke.getKeyStroke(KeyEvent.VK_C, MASK));
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            image = null;
            revalidate();
            repaint();
        }
    }

    private class ImageOpenAction extends AbstractAction {

        public ImageOpenAction(String name) {
            super(name);
            this.putValue(Action.MNEMONIC_KEY, KeyEvent.VK_O);
            this.putValue(Action.ACCELERATOR_KEY,
                KeyStroke.getKeyStroke(KeyEvent.VK_O, MASK));
        }

        @Override
        public void actionPerformed(ActionEvent e) {
            int returnVal = chooser.showOpenDialog(chooser);
            if (returnVal == JFileChooser.APPROVE_OPTION) {
                File f = chooser.getSelectedFile();
                try {
                    image = ImageIO.read(f);
                    revalidate();
                    repaint();
                } catch (IOException ex) {
                    ex.printStackTrace(System.err);
                }
            }
        }
    }
}

Answer 3

fileSelect.showOpenDialog(this)

Of course, this must be a Component of some sort (the JFrame or JPanel of your main interface). All dialogs need to have a parent component if you wish them to come to the front.

Answer 4

I'm not sure what your problem actually is (it's probably your Netbeans.... who knows), but have you tried overriding the createDialog method?

Example:

JFileChooser fc = new JFileChooser() {
   @Override
   protected JDialog createDialog(Component parent) throws HeadlessException {
       // intercept the dialog created by JFileChooser
       JDialog dialog = super.createDialog(parent);
       dialog.setModal(true);  // set modality (or setModalityType)
       return dialog;
   }
};

This is merely a hack solution, you should not need to do that ordinarily.