Swing Hacks

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Chapter 4, File Choosers

#31 Add Image Preview to File Choosers

HACK

H A C K

#31

Add Image Preview to File Choosers

Hack #31

This hack will show you how to add an image previewer to a JFileChooser,

and it will set you on the way toward building your own customizations.

We’ve already talked about

JFileChooser

’s numerous limitations. Not sur-

prisingly, many applications have their own custom choosers and exten-

sions to support things like image previews. The standard

JFileChooser was

designed to mimic only the most common features, but it does provide a

way to add your own enhancements.

The standard

JFileChooser looks like most native file choosers. It has a

directory selector, a list of files, and select and close buttons. There may also

be a toolbar of sorts. If you want to build your own customized file chooser,

you could do it the same way platform-specific file choosers are imple-

mented—through L&F code. This would entail subclassing

javax.swing.

plaf.basic.BasicFileChooserUI

, working around the private methods, and

possibly reimplementing the whole thing, none of which is easy or fun. For-

tunately, the

JFileChooser API provides a simple extension hook in the form

of the

setAccesory( ) method. This method lets you add any JComponent to

an existing

JFileChooser, thereby adding your own features without muck-

ing around in file chooser code.

In this hack, you’ll learn how to create an image previewer. ...