Java IO.pdf - Nguyen Dang Binh

13.3 File Viewer, Part 6
Java I/O
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 text area.
Figure 13.6. The FileViewer
One fact I discovered while developing this application was that Swing components don't get
along well with standard AWT components like Frame and TextArea. My initial attempts that
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