Calling GetOpenFileName via JNA is not suitable for a Swing application

Question

I am trying to use the native Windows file dialog in Java, using JNA to call the comdlg32 GetOpenFileName function. I made a static OpenFileDialog.display method that looks like this:

  public static List<File> display(Window parent, boolean allowMultiSelect) 

It should return the selected files, or null if the user canceled the dialog.

I have two simple test programs. This works as expected:

 package nativedialogs; import java.io.File; import java.util.List; public class SimpleTest { public static void main(String[] args) { List<File> files = OpenFileDialog.display(null, true); System.out.println(files); } } 

This, however, does not mean:

 package nativedialogs; import java.awt.event.ActionEvent; import java.awt.event.ActionListener; import java.io.File; import java.util.List; import javax.swing.JButton; import javax.swing.JFrame; import javax.swing.SwingUtilities; public class SwingTest { public static void main(String[] args) { SwingUtilities.invokeLater(new Runnable() { @Override public void run() { JFrame f = new JFrame(); f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); JButton button = new JButton("Open file dialog"); button.addActionListener(new ActionListener() { @Override public void actionPerformed(ActionEvent e) { List<File> files = OpenFileDialog.display(f, true); // These also fail: // List<File> files = OpenFileDialog.display(f, false); // List<File> files = OpenFileDialog.display(null, true); // List<File> files = OpenFileDialog.display(null, false); System.out.println(files); } }); f.add(button); f.pack(); f.setVisible(true); } }); } } 

In the last example, CommDlgExtendedError returns 2, which according to MSDN :

CDERR_INITIALIZATION 0x0002

During initialization, the function of the general dialog box failed. This error often occurs when there is not enough memory.

... which really doesn't help me much. What am I doing wrong here?

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I put other sources in the PasteBin so that I don’t confuse the question too much:

OpenFileDialog : http://pastebin.com/HDmu0TjX

ComDlg32JNA : http://pastebin.com/X5F5LLip

Answer 1

Better not to do any JNA code from Swing EDT. Try using SwingWorker to start a dialog in the background thread.

I would try to help more, but there is no comdlg32 on my Win 7 64-bit version :(