Pop-Ups and Choosers - The Definitive Guide to Java Swing - page 325

■ Tip Setting the FileFilter with setFileFilter() before adding filters with add

ChoosableFileFilter() causes the accept-all-file filter to be unavailable. To put it back, call
setAcceptAllFileFilterUsed(true) . In addition, you can reset the filter list with a call to
resetChoosableFileFilters() .

One built-in filter isn't a FileFilter . It concerns hidden files, such as those that begin with
a period ( . ) on UNIX file systems. By default, hidden files aren't shown within the JFileChooser .
To enable the display of hidden files, you must set the fileHidingEnabled property to false :

aFileChooser.setFileHidingEnabled(false);

■ Tip When creating javax.swing.filechooser.FileFilter subclasses, you may want to have the
new class also implement the java.io.FileFilter interface. To do this, simply add implements
java.io.FileFilter to the class definition. This works because the method signature for the accept()
method in the javax.swing.filechooser class matches the interface definition: public boolean
accept(File file) .

Choosing Directories Instead of Files
The JFileChooser supports three selection modes: files only, directories only, and files and
directories. The fileSelectionMode property setting determines the mode of the chooser. The
available settings are specified by the three JFileChooser constants: FILES_ONLY , DIRECTORIES_ONLY ,
and FILES_AND_DIRECTORIES . Initially, the file chooser is in JFileChooser.FILES_ONLY mode.
To change the mode, just call public void setFileSelectionMode(int newMode) .
In addition to the fileSelectionMode property, you can use the read-only
fileSelectionEnabled and directorySelectionEnabled properties to determine the type
of input currently supported by the file chooser.

Adding Accessory Panels
The JFileChooser supports the addition of an accessory component. This component can
enhance the functionality of the chooser, including previewing an image or document, or
playing an audio file. To respond to file selection changes, the accessory component should
attach itself as a PropertyChangeListener to the JFileChooser . When the JFileChooser. ➥
SELECTED_FILE_CHANGED_PROPERTY property changes, the accessory then changes to reflect the
file selection. Figure 9-28 shows how an image previewer accessory component might appear.
Configuring the accessory for a chooser is just like setting any other property.

fileChooser.setAccessory(new LabelAccessory(fileChooser));