Using a new Exception for handling unknown disk formats. This will make handling errors easier.

src/main/java/com/webcodepro/applecommander/storage/DiskUnrecognizedException.java

@@ -0,0 +1,38 @@
+/*
+ * AppleCommander - An Apple ][ image utility.
+ * Copyright (C) 2002 by Robert Greene
+ * robgreene at users.sourceforge.net
+ *
+ * This program is free software; you can redistribute it and/or modify it 
+ * under the terms of the GNU General Public License as published by the 
+ * Free Software Foundation; either version 2 of the License, or (at your 
+ * option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but 
+ * WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY 
+ * or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License along 
+ * with this program; if not, write to the Free Software Foundation, Inc., 
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+package com.webcodepro.applecommander.storage;
+
+/**
+ * A DiskUnrecognizedException is thrown when the Disk Image being opened is not recognized by any image handler.
+ * <br>
+ * Created at: Jan 8, 2018
+ * @author Lisias Toledo
+ */
+public class DiskUnrecognizedException extends DiskException {
+
+	private static final long serialVersionUID = 0xFFFFFFFF80000000L;
+
+	/**
+	 * Constructor for DiskFullException.
+	 */
+	public DiskUnrecognizedException(final String imagepath) {
+		super("DiskUnrecognizedException", imagepath);
+	}
+}

src/main/java/com/webcodepro/applecommander/ui/swt/SwtAppleCommander.java

@@ -39,6 +39,7 @@ import org.eclipse.swt.widgets.ToolItem;
 import com.webcodepro.applecommander.storage.Disk;
 import com.webcodepro.applecommander.storage.FormattedDisk;
 import com.webcodepro.applecommander.storage.Disk.FilenameFilter;
+import com.webcodepro.applecommander.storage.DiskUnrecognizedException;
 import com.webcodepro.applecommander.ui.AppleCommander;
 import com.webcodepro.applecommander.ui.UiBundle;
 import com.webcodepro.applecommander.ui.UserPreferences;
@@ -171,19 +172,31 @@ public class SwtAppleCommander implements Listener {
 			try {
 				Disk disk = new Disk(fullpath);
 				FormattedDisk[] formattedDisks = disk.getFormattedDisks();
-				if (formattedDisks != null) {
 				DiskWindow window = new DiskWindow(shell, formattedDisks, imageManager);
 				window.open();
-				} else {
+			} catch (DiskUnrecognizedException e) {
 				showUnrecognizedDiskFormatMessage(fullpath);
-				}
 			} catch (Exception ignored) {
 				ignored.printStackTrace();
-				showUnrecognizedDiskFormatMessage(fullpath);
+				showUnexpectedErrorMessage(fullpath);
 			}
 		}
 	}
 
+	/**
+	 * Displays the unrecognized disk format message.
+	 * @param fullpath
+	 */
+	protected void showUnexpectedErrorMessage(String fullpath) {
+		Shell finalShell = shell;
+		MessageBox box = new MessageBox(finalShell, SWT.ICON_ERROR | SWT.OK);
+		box.setText(textBundle.get("SwtAppleCommander.UnexpectedErrorTitle")); //$NON-NLS-1$
+		box.setMessage(
+			  textBundle.format("SwtAppleCommander.UnexpectedErrorMessage", //$NON-NLS-1$
+			  		fullpath));
+		box.open();
+	}
+
 	/**
 	 * Displays the unrecognized disk format message.
 	 * @param fullpath

src/main/resources/com/webcodepro/applecommander/ui/UiBundle.properties

@@ -270,7 +270,7 @@ GraphicsFilterAdapter.BadImageMessage=Unexpected graphic file encountered\!
 # SwtAppleCommander
 SwtAppleCommander.AppleCommander=AppleCommander
 SwtAppleCommander.UnrecognizedFormatTitle=Unrecognized Disk Format
-SwtAppleCommander.UnrecognizedFormatMessage=Unable to load "{0}".\n\nAppleCommander did not recognize the format\nof the disk.  Either this is a new format\nor a protected disk.\n\nSorry\!
+SwtAppleCommander.UnrecognizedFormatMessage=Unable to load "{0}".\n\nAppleCommander did not recognize the format of the disk.  Either this is a new format or a protected disk.\n\nSorry\!
 SwtAppleCommander.OpenDiskImageTooltip=Open a disk image (Ctrl+O)
 SwtAppleCommander.CreateDiskImageTooltip=Create a disk image (Ctrl+C)
 SwtAppleCommander.CompareDiskImageTooltip=Compare two disk images (Ctrl+E)