Blackberry Tab bar control - blackberry

Question

I want a tab bar in my application.I tried the sample code for it in blackberry but I want it at the bottom of the screen.I tried this code but it gives me uncaught runtime exception.Why this so? Whats the problem in this code?
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.ui.image.*;
import net.rim.device.api.ui.toolbar.*;
import net.rim.device.api.util.*;
import net.rim.device.api.system.*;
import net.rim.device.api.command.*;
public class ToolbarDemo extends UiApplication
{
public static void main(String[] args)
{
ToolbarDemo theApp = new ToolbarDemo();
theApp.enterEventDispatcher();
}
public ToolbarDemo()
{
// Push a screen onto the UI stack for rendering.
pushScreen(new ToolbarDemoScreen());
}
private final static class ToolbarDemoScreen extends MainScreen
{
public ToolbarDemoScreen()
{
if (ToolbarManager.isToolbarSupported())
{
setTitle("Toolbar Demo");
ToolbarManager manager = new ToolbarManager();
setToolbar(manager);
try
{
Bitmap myBitmap = Bitmap.getBitmapResource("myImg.jpg");
Image myImage = ImageFactory.createImage(myBitmap);
/*
* To create more buttons, Repeat the following lines
* up until manager.add()
*/
ToolbarButtonField button1 = new ToolbarButtonField(myImage, new StringProvider("butn1"));
button1.setCommandContext(new Object()
{
public String toString()
{
return "Button1";
}
});
button1.setCommand(new Command(new CommandHandler()
{
public void execute(ReadOnlyCommandMetadata metadata, Object context)
{
Dialog.alert("Executing command for " + context.toString());
}
}));
manager.add(new ToolbarSpacer(0));
manager.add(button1);
}
catch (Exception e)
{
System.out.println(e.getMessage());
}
}
else
{
Dialog.alert("The Toolbar is not supported on this device.");
}
}
}
}

Answer 1

If you are getting the Exception, Uncaught Exception: pushModalScreen called by a non-event thread then you can try following code snippet for displaying an alert.
UiApplication.getUiApplication().invokeLater(new Runnable() {
public void run() {
Dialog.alert("The Toolbar is not supported on this device.");
}
});
And please check this question, “pushModalScreen called by a non-event thread” thrown on event thread.

Answer 2

Try this code
EncodedImage e1 = EncodedImage.getEncodedImageResource("home.png");
EncodedImage e2 = EncodedImage.getEncodedImageResource("map.png");
EncodedImage e3 = EncodedImage.getEncodedImageResource("members.png");
EncodedImage e4 = EncodedImage.getEncodedImageResource("message.png");
EncodedImage e5 = EncodedImage.getEncodedImageResource("settings.png");
EncodedImage e6 = EncodedImage.getEncodedImageResource("logout.png");
HorizontalFieldManager buttonPanel = new HorizontalFieldManager(Field.FIELD_TOP | Field.USE_ALL_WIDTH);
VerticalFieldManager vfm=new VerticalFieldManager();
vfm.add(new LabelField("Map"));
vfm.add(new BitmapField(e2.getBitmap(),FOCUSABLE){
protected boolean navigationClick(int status, int time){
Dialog.alert("MAP");
return true;
}
});
buttonPanel.add(vfm);
buttonPanel.add(new LabelField(" "));
VerticalFieldManager vfm1=new VerticalFieldManager();
vfm1.add(new LabelField("Members"));
vfm1.add(new BitmapField(e3.getBitmap(),FOCUSABLE){
protected boolean navigationClick(int status, int time){
Dialog.alert("Members");
return true;
}
});
buttonPanel.add(vfm1);
VerticalFieldManager vfm2=new VerticalFieldManager();
vfm2.add(new LabelField("Message"));
vfm2.add(new BitmapField(e4.getBitmap(),FOCUSABLE){
protected boolean navigationClick(int status, int time){
Dialog.alert("Message");
return true;
}
});
buttonPanel.add(vfm2);
VerticalFieldManager vfm3=new VerticalFieldManager();
vfm3.add(new LabelField("Settings"));
vfm3.add(new BitmapField(e5.getBitmap(),FOCUSABLE){
protected boolean navigationClick(int status, int time){
Dialog.alert("Settings");
return true;
}
});
buttonPanel.add(vfm3);
VerticalFieldManager vfm4=new VerticalFieldManager();
vfm4.add(new LabelField("Logout"));
vfm4.add(new BitmapField(e6.getBitmap(),FOCUSABLE){
protected boolean navigationClick(int status, int time){
Dialog.alert("Logout");
return true;
}
});
buttonPanel.add(vfm4);
setStatus(buttonPanel);