Decision Making and Repetition with Reusable Objects - Java Programming: Comprehensive Concepts and Techniques - page 270

To Construct Applet Components

1. Enter lines 23 through 36 as shown in Figure 4-42 on the previous page.
TextPad displays the code to construct the components (Figure 4-43).The
Checkbox constructors use the variable, codeGroup, to include the four
Checkboxes as members of the CheckboxGroup named codeGroup.

constructor code
to add Labels, a
TextField, and
Checkboxes in a
CheckboxGroup

FIGURE 4-43

Table 4-14 displays some of the methods used with a Checkbox. For infor-
mation on other methods, the Java API contains a table associated with each
component.

Table 4-14 Methods Used with the Checkbox Component

METHOD PURPOSE EXAMPLE

setState() To set or determine whether

boolean answer = myOption.getState();

getState() the Checkbox is selected

setLabel() To set or determine the myOption.setLabel("This is the new caption");

getLabel() caption of a Checkbox

addItemListener() Allows the Checkbox to

myCheckbox.addItemListener();

become a trigger for an event

Adding Color, Components, Focus, and Listeners
to the Applet

You may recall that the add() method takes an argument of a declared
component and adds it to the Applet Viewer window when the applet is initi-
ated. The addItemListener event then causes the applet to listen for clicks
initiated by the user. When the click occurs, a series of associated objects and
methods change, including the getState() method, the itemStateChanged()
method, and the ItemEvent() object. Table 4-15 describes the general form of
the addItemListener event.