Implementation of MapField in Blackberry

import javax.microedition.location.Coordinates;

import net.rim.device.api.lbs.*;
import net.rim.device.api.ui.*;
import net.rim.device.api.ui.component.*;
import net.rim.device.api.ui.container.*;
import net.rim.device.api.system.*;

public class MapFielddemo extends UiApplication
{
public static void main(String[] args)
{
MapFielddemo theApp = new MapFielddemo();
theApp.enterEventDispatcher();
}

MapFielddemo()
{
pushScreen(new myScreen());
}
}

class myScreen extends FullScreen implements FieldChangeListener
{
private MapField _mapField;
private ButtonField _zoomIn;
private ButtonField _zoomOut;
private double _prevLat = 30.721596105585;
private double _prevLon = 76.710104942322;// positions of city in india, so if you want to try it please zoom out when you run this code.
private int _prevZoom = 4;

myScreen()
{
super(DEFAULT_MENU | DEFAULT_CLOSE);
createUI();
}

private void createUI()
{
Coordinates cord = new Coordinates(_prevLat,_prevLon,0);
VerticalFieldManager vfm;

synchronized (Application.getEventLock())
{
vfm = new VerticalFieldManager
(Manager.USE_ALL_WIDTH | Manager.USE_ALL_HEIGHT);
_mapField = new MapField();
_mapField.setPreferredSize(_mapField.getPreferredWidth(),
(int)(Display.getHeight() * 0.91));
vfm.add(_mapField);
}

FlowFieldManager ffm = new FlowFieldManager();
ffm.add(_zoomIn = new ButtonField("Zoom In",ButtonField.CONSUME_CLICK));
_zoomIn.setChangeListener(this);

ffm.add(_zoomOut = new ButtonField("Zoom Out",ButtonField.CONSUME_CLICK));
_zoomOut.setChangeListener(this);



vfm.add(ffm);
add(vfm);

_mapField.moveTo(cord);


_mapField.setZoom(_prevZoom);
}

public void fieldChanged(Field field, int context)
{
if (field == _zoomIn)
{
_mapField.setZoom(Math.max(_mapField.getZoom() - 1,
_mapField.getMinZoom()));
}
else if (field == _zoomOut)
{
_mapField.setZoom(Math.min(_mapField.getZoom() + 1,
_mapField.getMaxZoom()));
}




}
}