| ID | CS000957 | Creation date | May 14, 2008 |
| Platform | S60 3rd Edition, MR S60 3rd Edition, FP1 | Tested on devices | Nokia E61i Nokia N95 8GB |
| Category | Java ME | Subcategory | Hardware |
| Keywords (APIs, classes, methods, functions): javax.microedition.lcdui.Display, javax.microedition.lcdui.Display.flashBacklight() |
This snippet demonstrates how to flash the backlight of the device for a specified duration. In practice, the MIDlet constructs a menu item through which the user can flash the backlight.
Flashing the backlight can be implemented as follows:
// Flash the backlight for 5 seconds
Display.getDisplay(this).flashBacklight(5000);
Here is a complete example:
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.midlet.MIDlet;
public class ExampleMIDlet extends MIDlet implements CommandListener {
private Command flashCommand;
private Command exitCommand;
private Form mainForm;
/**
* Constructor. Constructs the object and initializes displayables.
*/
public ExampleMIDlet() {
mainForm = new Form("ExampleMIDlet");
flashCommand = new Command("Flash", Command.SCREEN, 0);
mainForm.addCommand(flashCommand);
exitCommand = new Command("Exit", Command.EXIT, 0);
mainForm.addCommand(exitCommand);
mainForm.setCommandListener(this);
}
/**
* Called when the MIDlet is started.
*/
public void startApp() {
Display.getDisplay(this).setCurrent(mainForm);
}
// Other inherited methods omitted for brevity
// ...
/**
* From CommandListener.
* Called by the system to indicate that a command has been invoked on a
* particular displayable.
* @param command the command that was invoked
* @param displayable the displayable where the command was invoked
*/
public void commandAction(Command command, Displayable displayable) {
if (command == flashCommand) {
// Flash the backlight for 5 seconds
boolean flashAllowed = Display.getDisplay(this).flashBacklight(5000);
if (!flashAllowed) {
// TODO: Flashing is not allowed. Inform the user.
}
} else if (command == exitCommand) {
// Exit the MIDlet
destroyApp(true);
notifyDestroyed();
}
}
If the user selects the Flash menu item, the backlight is flashed for 5 seconds.