Geertjan's Blog

  • August 20, 2012

Open File Action

Geertjan Wielenga
Product Manager

Let's create a simple NetBeans Platform application for opening files. We assume we need an "Open File" action, rather than using the Favorites window to open files, which would work just as well, if not better.

  1. Use the NetBeans Platform Application template in the New Project dialog to create a skeleton NetBeans Platform application.

  2. Add a new module and set dependencies on Datasystems API, File System API, Lookup API, Nodes API, UI Utilities API, and Utilities API.

  3. In the new module, define the class below:
    import java.awt.event.ActionEvent;
    import java.awt.event.ActionListener;
    import java.io.File;
    import org.openide.awt.ActionID;
    import org.openide.awt.ActionReference;
    import org.openide.awt.ActionRegistration;
    import org.openide.cookies.OpenCookie;
    import org.openide.filesystems.FileChooserBuilder;
    import org.openide.filesystems.FileUtil;
    import org.openide.loaders.DataObject;
    import org.openide.loaders.DataObjectNotFoundException;
    import org.openide.util.Exceptions;
    import org.openide.util.NbBundle.Messages;
    @ActionID(category = "File", id = "org.mycore.OpenFileAction")
    @ActionRegistration(displayName = "#CTL_OpenFileAction")
    @ActionReference(path = "Menu/File", position = 10)
    @Messages("CTL_OpenFileAction=Open File")
    public final class OpenFileAction implements ActionListener {
    public void actionPerformed(ActionEvent e) {
    //The default dir to use if no value is stored
    File home = new File(System.getProperty("user.home"));
    //Now build a file chooser and invoke the dialog in one line of code
    //"user-dir" is our unique key
    File toAdd = new FileChooserBuilder("user-dir").setTitle("Open File").
    //Result will be null if the user clicked cancel or closed the dialog w/o OK
    if (toAdd != null) {
    try {
    } catch (DataObjectNotFoundException ex) {
  4. Add the "image" module, which is in the "ide" cluster, in the Libraries tab of the application's Project Properties dialog.

Run the application. Choose File | Open File and then browse on disk to the files of your choice. Depending on whether you have support for the related file type, e.g., you're able to open image files because of the "image" module added above, the file will open in the application's editor mode.

Read this related blog entry for a different approach!

Join the discussion

Comments ( 5 )
  • guest Tuesday, April 2, 2013

    How do you combine this with your own FileType (e.g. AbcFileType) so that the file selected is opened in an appropriate editor, your own?


  • Geertjan Monday, April 15, 2013

    Hi Hakan, the file should automatically open in your own editor. Nothing needs to be done for that. Go to the New File dialog, select your file on disk, and then it will be opened in the editor you created for it.

  • Javier Thursday, May 22, 2014

    Hi!, thank for your post

    please, I have a problem loading xml-file "java.lang.IllegalArgumentException: We expect CloneableEditorSupport in org.openide.nodes.FilterNode$FilterLookup@106d267"

  • guest Friday, May 30, 2014

    Hi Javier,

    I just got the same error message.

    The solution is to add the "XML Multiview Editor" module to your platform app project.

    right click on your platform app project -> properties -> libraries -> ide -> check XML Multiview Editor -> clean and build


  • Nico Friday, May 30, 2014

    BTW: this class is not necessary at all.

    Add the User Utilities module in the ide section and you have an image viewer without a single line of code.


Please enter your name.Please provide a valid email address.Please enter a comment.CAPTCHA challenge response provided was incorrect. Please try again.