Java Tips - How to control volume of the mobile device

This Java tip covers the aspect of controling the volume of a mobile device. VolumeControl is an interface for manipulating the audio volume of a Player. Developer may use this as an add-in for its applications.

import javax.microedition.midlet.*;

import javax.microedition.lcdui.*;

import javax.microedition.lcdui.Ticker;

import javax.microedition.media.*;



public class VolumeControlDemo extends MIDlet implements CommandListener {

    

    private Display display;

    private Command exit,incr,decr;

    Form frm;

    

    VolumeControl vc;

    int vol;

    Player player;

    

    public VolumeControlDemo() {

        display = Display.getDisplay(this);

        

    }

    

    public void startApp() {

        

        frm=new Form("VolumeControlDemo  Demo");

        

        exit= new Command("Exit",Command.EXIT,1);

        decr= new Command("Decrease",Command.EXIT,1);

        incr= new Command("Increase",Command.EXIT,1);

        frm.addCommand(exit);

        frm.addCommand(decr);

        frm.addCommand(incr);

        

        frm.setCommandListener(this);

        

        

        display.setCurrent(frm);

        

        try {

            

            // Creating player object

            player = Manager.createPlayer("/demo.wav");

            

            // Setting loop count

            player.setLoopCount(-1);

            

            // Start sound

            player.start();

            Control cs[];

            

            // Getting Controls object

            cs = player.getControls();

            

            for (int i = 0; i < cs.length; i++) {

                if (cs[i] instanceof VolumeControl)

                    // Getting volume control

                    vc=(VolumeControl)cs[i];

            }

            

        } catch (Exception e) {}

        

    }

    

    public void pauseApp() {

        

    }

    

    public void destroyApp(boolean un) {

        

    }

    

    public void commandAction(Command cmd,Displayable d) {

        try {

            if(decr) {

                if(vol>0) vol--;

                vc.setLevel(vol);

            } else if() {

                if(vol<99) vol--;

                vc.setLevel(vol);

            }

            

            frm.appent("vol="+vc.getLevel());

        }catch(Exception e){}

        

    }

}
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