Graphical User Interfaces - JavaTech: An Introduction to Scientific and Technical Computing with Java - page 218

group.add (fBlue);
add (fBlue);
} // ctor
/** Action events come here when the user clicks
*onabutton.
**/
public void actionPerformed (ActionEvent evt) {
// Default color component values.
int cr=0;
int cg=0;
int cb=0;
// Only one button can be selected at a time
// so find the button and set the corresponding
// output panel color.
Object source = evt.getSource ();
if (source == fRed)
cr = 0xFF;
else if (source == fGreen)
cg = 0xFF;
else if (source == fBlue)
cb = 0xFF;
fOutputPanel.setColor (cr,cg,cb);
} // actionPerformed
} // class RadioButtonsPanel
7.3.3 JList
The JList component provides a list of items from which the user can select.
Depending on how the JList is configured, either a single item or multiple items
can be selected. This time we tell UiTestApplet to use ListApplet ,which
creates the interface shown in Figure 7.6. The user can select one of five colors
in a JList . The ListPanel code is given below.
One constructor of JList takes an Object array as a parameter. The ele-
ments of the array become the list items. We'll use a String array. The
number of items that will be visible depends on the value passed to the
setVisibleRowCount() method. The setSelectionModel() is used to
configure the list to be either single- or multiple-selection mode, and the initial
item selected is set with setSelectedIndex() .