Use the JColorChooser class to enable users to choose from a palette of colors. A color chooser is a component that you can place anywhere within your program GUI. The JColorChooser API also makes it easy to bring up a dialog (modal or not) that contains a color chooser.
Here is a picture of an application that uses a color chooser to set the text color in a banner:
The source code for the program is in ColorChooserDemo.java.
The color chooser consists of everything within the box labeled Choose Text Color. This is what a standard color chooser looks like in the Java Look & Feel. It contains two parts, a tabbed pane and a preview panel. The three tabs in the tabbed pane select chooser panels. The preview panel below the tabbed pane displays the currently selected color.
Here is the code from the example that creates a JColorChooser instance and adds it to a container:
public class ColorChooserDemo extends JPanel ... {
public ColorChooserDemo() {
super(new BorderLayout());
banner = new JLabel("Welcome to the Tutorial Zone!",
JLabel.CENTER);
banner.setForeground(Color.yellow);
. . .
tcc = new JColorChooser(banner.getForeground());
. . .
add(tcc, BorderLayout.PAGE_END);
}
The JColorChooser constructor in the previous code snippet takes a Color argument, which specifies the chooser's initially selected color. If you do not specify the initial color, then the color chooser displays Color.white. See the Color API documentation for a list of color constants you can use.
A color chooser uses an instance of ColorSelectionModel to contain and manage the current selection. The color selection model fires a change event whenever the user changes the color in the color chooser. The example program registers a change listener with the color selection model so that it can update the banner at the top of the window. The following code registers and implements the change listener:
tcc.getSelectionModel().addChangeListener(this);
. . .
public void stateChanged(ChangeEvent e) {
Color newColor = tcc.getColor();
banner.setForeground(newColor);
}
See How to Write a Change Listener for general information about change listeners and change events.
A basic color chooser, like the one used in the example program, is sufficient for many programs. However, the color chooser API allows you to customize a color chooser by providing it with a preview panel of your own design, by adding your own chooser panels to it, or by removing existing chooser panels from the color chooser. Additionally, the JColorChooser class provides two methods that make it easy to use a color chooser within a dialog.
The rest of this section discusses these topics:
Now let's turn our attention to ColorChooserDemo2, a modified version of the previous demo program that uses more of the JColorChooser API.
Here is a picture of ColorChooserDemo2:
This program customizes the banner text color chooser in these ways:
Removing or Replacing the Preview Panel covers the first customization. Creating a Custom Chooser Panel discusses the last two.
This program also adds a button that brings up a color chooser in a dialog, which you can use to set the banner background color.
Showing a Color Chooser in a DialogThe JColorChooser class provides two class methods to make it easy to use a color chooser in a dialog. ColorChooserDemo2 uses one of these methods, showDialog, to display the background color chooser when the user clicks the Show Color Chooser... button. Here is the single line of code from the example that brings up the background color chooser in a dialog:
Color newColor = JColorChooser.showDialog(
ColorChooserDemo2.this,
"Choose Background Color",
banner.getBackground());
The first argument is the parent for the dialog, the second is the dialog title, and the third is the initially selected color.
The dialog disappears under three conditions: the user chooses a color and clicks the OK button, the user cancels the operation with the Cancel button, or the user dismisses the dialog with a frame control. If the user chooses a color, the showDialog method returns the new color. If the user cancels the operation or dismisses the window, the method returns null. Here is the code from the example that updates the banner background color according to the value returned by showDialog:
if (newColor != null) {
banner.setBackground(newColor);
}
The dialog created by showDialog is modal. If you want a non-modal dialog, you can use JColorChooser's createDialog method to create the dialog. This method also lets you specify action listeners for the OK and Cancel buttons in the dialog window. Use JDialog's show method to display the dialog created by this method. For an example that uses this method, see Specifying Other Editors in the How to Use Tables section.
By default, the color chooser displays a preview panel. ColorChooserDemo2 removes the text color chooser's preview panel with this line of code:
tcc.setPreviewPanel(new JPanel());
This effectively removes the preview panel because a plain JPanel has no size and no default view. To set the preview panel back to the default, use null as the argument to setPreviewPanel.
To provide a custom preview panel, you also use setPreviewPanel. The component you pass into the method should inherit from JComponent, specify a reasonable size, and provide a customized view of the current color. To get notified when the user changes the color in the color chooser, the preview panel must register as a change listener on the color chooser's color selection model as described previously.
The default color chooser provides five chooser panels:
You can extend the default color chooser by adding chooser panels of your own design with addChooserPanel, or you can limit it by removing chooser panels with removeChooserPanel.
If you want to remove all of the default chooser panels and add one or more of your own, you can do this with a single call to setChooserPanels. ColorChooserDemo2 uses this method to replace the default chooser panels with an instance of CrayonPanel, a custom chooser panel. Here is the call to setChooserPanels from that example:
//Override the chooser panels with our own.
AbstractColorChooserPanel panels[] = { new CrayonPanel() };
tcc.setChooserPanels(panels);
The code is straightforward: it creates an array containing the CrayonPanel. Next the code calls setChooserPanels to set the contents of the array as the color chooser's chooser panels.
CrayonPanel is a subclass of AbstractColorChooserPanel and overrides the five abstract methods defined in its superclass:
void buildChooser()
void updateChooser()
public void updateChooser() {
Color color = getColorFromModel();
if (Color.red.equals(color)) {
redCrayon.setSelected(true);
} else if (Color.yellow.equals(color)) {
yellowCrayon.setSelected(true);
} else if (Color.green.equals(color)) {
greenCrayon.setSelected(true);
} else if (Color.blue.equals(color)) {
blueCrayon.setSelected(true);
}
}
String getDisplayName()
getDisplayName method:
public String getDisplayName() {
return "Crayons";
}
Icon getSmallDisplayIcon()
null.
Icon getLargeDisplayIcon()
null.
The following tables list the commonly used JColorChooser constructors and methods. Other methods you might call are listed in the API tables in The JComponent Class. The API for using color choosers falls into these categories:
Color.white. Use the second constructor to specify a different initial color. The ColorSelectionModel argument, when present, provides the color chooser with a color selection model. Color showDialog(Component, String, Color) Create and show a color chooser in a modal dialog. The Component argument is the parent of the dialog, the String argument specifies the dialog title, and the Color argument specifies the chooser's initial color. JDialog createDialog(Component, String,showDialog, the Component argument is the parent of the dialog and the String argument specifies the dialog title. The other arguments are as follows: the boolean specifies whether the dialog is modal, the JColorChooser is the color chooser to display in the dialog, the first ActionListener is for the OK button, and the second is for the Cancel button. Examples that Use Color Choosers
This table shows the examples that use JColorChooser and where those examples are described.
showDialog. TableDialogEditDemo How to Use Tables Shows how to use a color chooser as a custom cell editor in a table. The color chooser used by this example is created with createDialog. BasicDnD Introduction to DnD Uses a color chooser that is not in a dialog; demonstrates default drag-and-drop capabilities of Swing components, including color choosers.
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