Buttons

Buttons represent a vivid and intuitive method to allow the user to interact with a program. The main point of interest for the programmer is the internal behaviour of these buttons, e.g. the triggering of ActionEvents or updating of the view.

JControl/Vole provides 3 basic types of buttons: The simple Button, the RadioButton and the CheckBox. These types are discussed in detail in the further course of this section and their functionality are presented using examples.

  • Button: The class Button creates a standard pushbutton labeled either by a String or an image (Resource). The buttons' content will be centered automatically. If the parameters width and height are omitted in the constructor, the Button will calculate its preferred size. Buttons will fire BUTTON_PRESSED ActionEvents if the are pressed.


  • RadioButton: The RadioButton is a special kind of Button, consisting of a graphical switch (that can be turned either on or off) and a following String. Adding multiple RadioButtons to a Container will cause the Container to autonomous make sure that only one of them will be active at a time. RadioButtons fire STATE_CHANGED ActionEvents if they are operated.


  • CheckBox: A CheckBox is a Button that can be activated or deavtivated. Its current state is symbolized by a check mark (mark present = active). Altering the state of a CheckBox will cause it to fire a STATE_CHANGED ActionEvent.


The following source code shows a program example that demonstrates the use of all three types of Buttons.

Figure 1 shows a screenshot of the VoleButtonExample program running on a JControl/Sticker device. To try the Look&Feel of JControl/Vole yourself, download the archive VoleButtonExample.zip and open the project file VoleButtonExample.jcp in your JControl/IDE. Then start the simulator or upload the project to your JControl device.

Figure 1: The VoleButtonExample

1    import jcontrol.ui.vole.Border;
2    import jcontrol.ui.vole.Button;
3    import jcontrol.ui.vole.CheckBox;
4    import jcontrol.ui.vole.Container;
5    import jcontrol.ui.vole.Frame;
6    import jcontrol.ui.vole.RadioButton;
7    
8    /**
9     * <p>This example demonstrates how to use buttons
10     * within the GUI framework JControl/Vole.</p>
11     *
12     * <p>(C) DOMOLOGIC Home Automation GmbH 2003-2005</p>
13     */
14    public class VoleButtonExample extends Frame {
15     
16      /**
17       * Create different kinds of buttons.
18       */
19      public VoleButtonExample() {
20        // create a simple button and add it to the frame
21        Button simpleButton = new Button("Press me!", 30, 45, 65, 12);
22        this.add(simpleButton);
23       
24        // create a Container with three RadioButtons
25        // and a Border around it
26        Container c1 = new Container();
27           
28        RadioButton rb1 = new RadioButton("Radio 1", 5, 8);
29        RadioButton rb2 = new RadioButton("Radio 2", 5, 18);
30        RadioButton rb3 = new RadioButton("Radio 3", 5, 28);
31       
32        // add the RadioButtons to the Container   
33        c1.add(rb1);
34        c1.add(rb2);
35        c1.add(rb3);
36       
37        // add a Border
38        c1.add(new Border("RadioButtons", 0, 0, 60, 40)); 
39       
40        // add the Container to the Frame
41        this.add(c1);
42       
43       
44        // create a Container with two CheckBoxes and a Border around it
45        Container c2 = new Container();
46    
47        CheckBox cb1 = new CheckBox("Check 1", 69, 10);
48        CheckBox cb2 = new CheckBox("Check 2", 69, 23);
49    
50        // add the CheckBoxes to the Container   
51        c2.add(cb1);
52        c2.add(cb2);
53       
54        // add a Border
55        c2.add(new Border("CheckBoxes", 64, 0, 60, 40));
56       
57        // add the second Container to the Frame
58        this.add(c2);
59      }
60    
61      /**
62       * Instantiate the VoleButtonExample.
63       */
64      public static void main(String[] args) {
65        VoleButtonExample vbe = new VoleButtonExample();
66        // make the Frame visible
67        vbe.show();
68      }
69    }
Listing 1: VoleButtonExample.java