Desktop API

Question

Hi guys,
How can I check whether any given file type is supported, before actually opening it.
The open method opens the file straight away, and in case the file hasn't any associated application it raises an exception, but there is no what that I am aware of that lets me query the os to know if it "undestands" the file.
Thanks,
MeTitus

Answer 1

I looked at the source for the Desktop class before:
    private static void checkFileValidation(File file){
        if (file == null) throw new NullPointerException("File must not be null");
        if (!file.exists()) {
            throw new IllegalArgumentException("The file: "
                                               + file.getPath() + " doesn't exist.");
        file.canRead();
    private void checkActionSupport(Action actionType){
        if (!isSupported(actionType)) {
            throw new UnsupportedOperationException("The " + actionType.name()
                                                    + " action is not supported on the current platform!");
    private void checkAWTPermission(){
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(new AWTPermission(
                                   "showWindowWithoutWarningBanner"));
    public void open(File file) throws IOException {       
        checkAWTPermission();
        checkExec();
        checkActionSupport(Action.OPEN);
        checkFileValidation(file);
        peer.open(file);
    private void checkExec() throws SecurityException {
        SecurityManager sm = System.getSecurityManager();
        if (sm != null) {
            sm.checkPermission(new FilePermission("<<ALL FILES>>",
                                                  SecurityConstants.FILE_EXECUTE_ACTION));
    }But the method that actually opens the file is provided by the DesktopPeer.open() method which is implemented natively, so I really think that there is not way to get this done the way it was supposed to be, lets just hope they add some more usufull methods to the Desktop class.