This method of the UserFileDialog Class displays a dialog box that allows the user to open a file for reading. If the user selects a file, then a FileInputStream object for that file is returned. If the user cancels the dialog box, null is returned. To determine the name of the file that was opened, you can use the getFileName method.
public synchronized FileInputStream openFileForReading() throws IOException;
Returns a FileInputStream object if the user selects a file or returns null if the user cancels the dialog box.
SecurityException if the caller does not have permission to initiate user-directed file I/O.
IOException if an I/O error occurs while attempting to open the file.