JFileChoosers and file extensions

[larry clay]

Hello guys, I've been testing things for a while since i'm learning java; I'm doing a playlist editor/creator and most of the problems I have are due to swing, and here comes my question. I used JFileChooser to open files without any problem, the FileNameExtensionFilters worked well, but now i'm a bit disoriented about what to do when saving with different file extensions, here's an example code:

				//Creating filechooser
				JFileChooser chooser = new JFileChooser();
				chooser.setCurrentDirectory(new File(".."));
				chooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
				
				//Adding extension filters
				FileNameExtensionFilter filterm3u = new FileNameExtensionFilter(
						"PLaylist file (.m3u)", "m3u");
				chooser.addChoosableFileFilter(filterm3u);
				FileNameExtensionFilter filterpls = new FileNameExtensionFilter(
						"PLaylist file (.pls)", "pls");
				chooser.addChoosableFileFilter(filterpls);

				try {
					int returnVal = chooser.showSaveDialog(frame);
					
					//If returnval is approved then I continue to save the file
					if (returnVal == JFileChooser.APPROVE_OPTION) {
						File SomeFile = chooser.getSelectedFile();
						String FilePath = SomeFile.getPath();

						//I use a getExtension method to get the file extension (won't work right now)
						if (getExtension(SomeFile).equalsIgnoreCase("m3u")) {
							System.out.println("Saving m3u file");
							// File export code
						}

						if (getExtension(SomeFile).equalsIgnoreCase("pls")) {
							System.out.println("Saving pls file");
							// File export code
						}

						System.out.println("File saved:" + SomeFile.getName());
					} else {
						if (returnVal == JFileChooser.ERROR
								|| returnVal == JFileChooser.ERROR_OPTION)
							System.out.println("Error saving file.");
						else
							System.out.println("Cancelled.");
					}
				} catch (Exception f) {
					f.printStackTrace();
					System.out.println("Error saving file.");
				}

This isn't working, it saves files without any extension unless I explicitly include the extension in the name when I select the file to save
I can already tell that the FileNameExtensionFilters only work when selecting files to be opened, but I still haven't figured out yet how to make extensions work. How can I force file extensions when saving according to the selected FileNameExtensionFilter? Any leads on this would be helpful, thanks in advance

[Darryl Burke]

JFileChooser gives you a selectedFile. Remember that a java.io.File isn't a computer file in the usual sense; the API makes it clear that it is (emphasis added)

An abstract representation of file and directory pathnames.

What you do with the pathname before you use it to create a physical file on disk is up to you. .

Most programs resort to appending a suitable extension if the user-selected file is not valid. You can easily do the same, using JFileChooser#getFileFilter() to get a reference to the selected filter; call its accept(File f) method to determine whether the file name is acceptable; if not, cast the reference and call FileNameExtensionFilter#getExtensions()[0] to get the desired extension.

[Campbell Ritchie]

And welcome to the Ranch

[larry clay]

Thanks for the help and welcome guys!

It works now and this is the corrected snippet. This only works with single extension filefilters since I only do a getExtensions()[0] method call. Filters with multiple extensions won't allow me to know which extension is the chosen one, neither the chosen File path if I don't explicitly name it with the desired extension so I can't do it this way ... I can't come with a workaround to this but neither do I need to implement it now. At least I know a little more about this matter now

			//Creating filechooser
			JFileChooser chooser = new JFileChooser();
			chooser.setCurrentDirectory(new File(".."));
			chooser.setFileSelectionMode(JFileChooser.FILES_ONLY);
			
			//Adding extension filters from an enum
			for(SaveFileFilters saveFilter: main.interfaz.util.SaveFileFilters.values()){
				chooser.addChoosableFileFilter(saveFilter.getFilter());
			}
				
			try
			{
				int returnVal = chooser.showSaveDialog(frmPrototipo);

				if ( returnVal == JFileChooser.APPROVE_OPTION )
				{
					PlaylistFile = chooser.getSelectedFile();
					FilePath = PlaylistFile.getPath();

				    FileFilter choosedFilter = chooser.getFileFilter();
				    boolean formatFlag = false;
				    
				    //Saving the file accoring the filefilter extension
					PlaylistFile = new File(FilePath + "." + ((FileNameExtensionFilter) choosedFilter).getExtensions()[0]);

					if (FileDir.getExtension(PlaylistFile).equalsIgnoreCase(
							"m3u")) {
						formatFlag = true;
						// File export code
					}

					if (FileDir.getExtension(PlaylistFile).equalsIgnoreCase(
							"pls")) {
						formatFlag = true;
						// File export code
					}

					if (FileDir.getExtension(PlaylistFile).equalsIgnoreCase(
							"txt")) {
						formatFlag = true;
						// File export code
					}

					if(formatFlag == false)
					{
						//Format not found. Showing error messages
						//This part should not be reached under normal circumstances
						consoleLog("Format invalid or nor found");
						Mensajes.MsgErr("Format invalid or nor found");
						// File export code (generic txt file)
					}
                                        else
					        consoleLog("File saved: "+ PlaylistFile.getName().toString());
				}
				else
				{
						if (returnVal == JFileChooser.ERROR
								|| returnVal == JFileChooser.ERROR_OPTION)
							System.out.println("Error saving file.");
						else
							System.out.println("Cancelled.");
				}		
			}
			catch ( Exception f )
			{
					f.printStackTrace();
					System.out.println("Error saving file.");
			}

[Darryl Burke]

larry clay wrote:This only works with single extension filefilters since I only do a getExtensions()[0] method call. Filters with multiple extensions won't allow me to know which extension is the chosen one

Use a separate filter for each extension and like I already said, use getFileFilter() to get the selected filter.