Java Reference
In-Depth Information
Listening for Color Selection Changes
The
JColorChooser
uses a
ColorSelectionModel
as its data model. As the following interface
definition shows, the data model includes a single property,
selectedColor
, for managing the
state of the color chooser.
public interface ColorSelectionModel {
// Listeners
public void addChangeListener(ChangeListener listener);
public void removeChangeListener(ChangeListener listener);
// Properties
public Color getSelectedColor();
public void setSelectedColor(Color newValue);
}
When a user changes the color within the
JColorChooser
, the
selectedColor
property changes,
and the
JColorChooser
generates a
ChangeEvent
to notify any registered
ChangeListener
objects.
Therefore, to complete the earlier
ColorSample
example in the previous section, and have
the foreground color of the label change when the user changes the color selection within the
JColorChooser
, you need to register a
ChangeListener
with the color chooser. This involves
creating a
ChangeListener
and adding it to the
ColorSelectionModel
. Placing the source code
shown in Listing 9-8 where the
//More source to come
comment appears in the Listing 9-7 is
necessary for this example to work properly.
Listing 9-8.
Activating the JColorChooser Example
ColorSelectionModel model = colorChooser.getSelectionModel();
ChangeListener changeListener = new ChangeListener() {
public void stateChanged(ChangeEvent changeEvent) {
Color newForegroundColor = colorChooser.getColor();
label.setForeground(newForegroundColor);
}
};
model.addChangeListener(changeListener);
Once this source is added, the example is complete. Running the program brings up
Figure 9-18, and selecting a new color alters the foreground of the label.
Creating and Showing a JColorChooser Pop-Up Window
Although the previous example is sufficient if you want to include a
JColorChooser
within your
own window, more often than not, you want the
JColorChooser
to appear in a separate pop-up
window. This window might appear as the result of selecting a button on the screen, or possibly
even selecting a menu item. To support this behavior, the
JColorChooser
includes the following
factory method:
public static Color showDialog(Component parentComponent,
String title, Color initialColor)
