Java I/O

File Viewer, Part 6

We’ve now got the tools needed to put a graphical user interface onto the FileViewer application we’ve been developing. The back end doesn’t need to change at all. It’s still based on the same filter streams we’ve used for the last several chapters. However, instead of reading filenames from the command line, we can get them from a file chooser. Instead of dumping the files on System.out, we can display them in a text area. And instead of relying on the user remembering a lot of confusing command-line switches, we can provide simple radio buttons for the user to choose from. This has the added advantage of making it easy to repeatedly interpret the same file according to different filters.

Figure 13.6 shows the finished application. This will give you some idea of what the code is aiming at. Initially, I started with a pencil-and-paper sketch, but I’ll spare you my inartistic renderings. The single JFrame window is organized with a border layout. The west panel contains various controls for determining how the data is interpreted. The east panel contains the JFileChooser used to select the file. Notice that the Approve button has been customized to say “View File” rather than “Open”. Ideally, I’d like to make the Cancel button say “Quit” instead, but the JFileChooser class doesn’t allow you to do that without using resource bundles, a subject I would prefer to leave for another book. The south panel contains a scroll pane. Inside the scroll pane is a streamed ...