1. Import the required classes and interfaces.

   import net.rim.blackberry.api.bbm.platform.*;
   import net.rim.blackberry.api.bbm.platform.service.*;
   import net.rim.device.api.ui.component.*;

2. Create a class that implements the PresenceListener interface and extends MainScreen. In the constructor for this screen class, pass in the application's associated BBMPlatformContext object.

   public class MyBBMContactListScreen implements PresenceListener extends MainScreen
   {
       public MyBBMContactListScreen(BBMPlatformContext platformContext) 
       {
   
       }
   }

3. In the constructor, invoke BBMPlatformContext.getContactListService().setPresenceListener() to assign the PresenceListener to your application.

   public class MyBBMContactListScreen implements PresenceListener
   {
       public MyBBMContactListScreen(BBMPlatformContext platformContext) 
       {
           platformContext.getContactListService().setPresenceListener(this);
       }
   }

4. In the MyBBMContactListScreen class, implement the PresenceListener.presenceUpdated() method. The following code displays a dialog box that informs the user of changes to a contact in your BlackBerry Messenger contact list. The following code sample uses a helper method, getEventName(), to parse the eventType parameter and return a readable String.

   public void presenceUpdated(BBMPlatformContact contact, int eventType)
   {
       final String str = "[" + getEventName(eventType) + "] was changed by " + contact.getDisplayName();
       Dialog.inform(str);
   }
   
   private String getEventName(int eventType)
   {
       String eventName;
   
       switch(eventType)
       {
           case PresenceListener.EVENT_TYPE_DISPLAY_PICTURE:
               eventName = "Display picture";
               break;
           
           case PresenceListener.EVENT_TYPE_DISPLAY_NAME:
               eventName = "Display name";
               break;
           
           case PresenceListener.EVENT_TYPE_PERSONAL_MESSAGE:
               eventName = "Personal Message";
               break;
           
           case PresenceListener.EVENT_TYPE_STATUS:
               eventName = "Status";
               break;
           
           default:
               eventName = "Default";
       }
   }

Code sample: Responding to a contact's changes in your contact list

import net.rim.blackberry.api.bbm.platform.*;
import net.rim.device.api.ui.component.*;

public class MyBBMContactListScreen implements PresenceListener
{
    public MyClass(BBMPlatformContext platformContext) 
    {
       platformContext.getContactListService().setPresenceListener(this);
    }

    public void presenceUpdated(BBMPlatformContact contact, int eventType)
    {
        final String str = "[" + getEventName(eventType) + "] was changed by " + contact.getDisplayName();
        Dialog.inform(str);
    }
 
    private String getEventName(int eventType)
    {
        String eventName;

        switch(eventType)
        {
            case PresenceListener.EVENT_TYPE_DISPLAY_PICTURE:
                eventName = "Display picture";
                break;
        
            case PresenceListener.EVENT_TYPE_DISPLAY_NAME:
                eventName = "Display name";
                break;
        
            case PresenceListener.EVENT_TYPE_PERSONAL_MESSAGE:
                eventName = "Personal Message";
                break;
        
            case PresenceListener.EVENT_TYPE_STATUS:
                eventName = "Status";
                break;
        
            default:
                eventName = "Default";
        }
    }
}