Please note that as of October 24, 2014, the Nokia Developer Wiki will no longer be accepting user contributions, including new entries, edits and comments, as we begin transitioning to our new home, in the Windows Phone Development Wiki. We plan to move over the majority of the existing entries. Thanks for all your past and future contributions.

Revision as of 04:37, 8 August 2013 by hamishwillee (Talk | contribs)

(diff) ← Older revision | Latest revision (diff) | Newer revision → (diff)

Controlling Light settings in Java ME

From Wiki
Jump to: navigation, search

This snippet shows how to control the lighting on devices through the setLights() method of the DeviceControl class.

Article Metadata
Code ExampleTested with
Devices(s): Nokia 6131, Nokia N81, Nokia 701, Nokia Asha 305
Created: IlGolub (28 Nov 2008)
Reviewed: mtilli (15 Aug 2012)
Last edited: hamishwillee (08 Aug 2013)

Source file:

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 ControllingLightMIDlet extends MIDlet implements CommandListener {
* Command for setting light

private Command controllingLightCommand;
* exit midlet command

private Command exitCommand;
private Form mainForm;
* The ControllingLightMIDlet constructor.

public ControllingLightMIDlet() {
//Empty implementation
* Performs an action assigned to the Mobile Device - MIDlet Started point.

public void startMIDlet() {
* Switches a current displayable in a display. The Display instance is
* taken from getDisplay() method. This method is used by all actions
* in the design for switching displayable.
* @param nextDisplayable the Displayable to be set

public void switchDisplayable(Displayable nextDisplayable) {
Display display = getDisplay();
* From CommandListener.
* Called by a system to indicated 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 (displayable == mainForm) {
if (command == exitCommand) {
} else if(command == controllingLightCommand) {
//up light level from 0 to 100
for(int i = 0; i < 100; i++) {
// void setLights(int num, int level) is a static function of
// class that
//activates and deactivates the lights on the device.
//Parameter num indicates the number of the device light
//to control. Currently only one num parameter value is
//specified: num value 0 is used for controlling the
//screen backlight. Parameter level is a value between
//0-100, which indicates the brightness of the light.
//In many implementations, there are only two levels:
//on or off(Sony Ericsson). Value 0 indicates lights off
//for monochrome displays or the minimum brightness setting
//for color displays. All other level values (1-100) are
//used for turning the lights on, possibly with different
//brightness levels, depending on the value. A larger value
//always results in either the same brightness setting as a
//lower one, or a brighter setting. For many products,
//values 1-100 will just turn the lights on.
DeviceControl.setLights(0, i);
try {
} catch (InterruptedException ex) {
* Returns an initiliazed instance of mainForm component.
* @return the initialized component instance

public Form getForm() {
if (mainForm == null) {
mainForm = new Form("Lighting test!");
exitCommand = new Command("Exit", Command.EXIT, 0);
controllingLightCommand = new Command("Light", Command.SCREEN, 0);
return mainForm;
* Returns a display instance.
* @return the display instance.

public Display getDisplay () {
return Display.getDisplay(this);
* Exits MIDlet.

public void exitMIDlet() {
* From MIDlet.
* Called when MIDlet is started.
* Checks whether the MIDlet have been already started and
* initialize/starts or resumes the MIDlet.

public void startApp() {
* From MIDlet.
* Called when MIDlet is paused.

public void pauseApp() {
//Empty implementation
* From MIDlet.
* Called to signal the MIDlet to terminate.
* @param unconditional if true, then the MIDlet has to be unconditionally
* terminated and all resources has to be released.

public void destroyApp(boolean unconditional) {
//Empty implementation


This MIDlet implements a simple example of controlling the light property.

Turns off the light then raises the light level from 1 to 100.

Supplementary material

You can download this application and source code here: Controlling Light

Related articles:

Flashing the backlight using Java ME

How to block the screen saver

This page was last modified on 8 August 2013, at 04:37.
206 page views in the last 30 days.