The following steps describe how to assign tags to mappable items that are stored in a MapDataModel class. The visibility is set to display locations that have the "work" tag. The resulting map from the application is shown in the following image:

1. Import the required classes and interfaces.

   import net.rim.device.api.lbs.maps.*;
   import net.rim.device.api.lbs.maps.model.*;
   import net.rim.device.api.lbs.maps.ui.*;
   import net.rim.device.api.ui.*;
   import net.rim.device.api.ui.container.*;

2. Create the application framework by extending the UiApplication class. In main(), create an instance of the new class and invoke enterEventDispatcher() to enable the application to receive events. In the application constructor, invoke pushScreen() to display the custom screen for the application. The MapTagScreen, which is described in step 3, represents the custom screen.

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

3. Create the framework for the custom screen by extending the FullScreen class. In the constructor, invoke super() to create a default menu.

   class MapTagScreen extends FullScreen
   {
       public MapTagScreen() 
       {
           super(FullScreen.DEFAULT_CLOSE | FullScreen.DEFAULT_MENU | 
                   FullScreen.VERTICAL_SCROLL | FullScreen.VERTICAL_SCROLLBAR);

4. In the screen constructor, invoke MapFactory.getInstance() to create an instance of the MapFactory class, and then invoke generateRichMapField() to generate the map field. Invoke add() to add the RichMapField instance to the screen.

   RichMapField map = MapFactory.getInstance().generateRichMapField();
   add(map);

5. Invoke getModel() to create an instance of the MapDataModel class.

   MapDataModel data = map.getModel();

6. Create instances of the MapLocation class to define the locations. Pass the latitude, longitude, label, and description of each location to the MapLocation objects.

   MapLocation julieHome = new MapLocation( 43.47751, -80.54817, 
           "Julie - Home", null );
   MapLocation headOffice = new MapLocation( 43.47550, -80.53900, 
           "Head Office", null );

7. Create an integer identifier to represent a mappable item. Assign the mappable item to the identifier by invoking add() to add a location and pass one of the MapLocation objects and a tag for the location to MapDataModel. You can use the identifier to access the item in MapDataModel and assign another tag to a mappable item by invoking tag(), and passing as arguments the identifier and the tag. In the following code sample, two locations are added to MapDataModel, and each location is assigned two tags.

   int julieHomeId = data.add( (Mappable) julieHome, "julie" );
   data.tag( julieHomeId, "home" );
   int headOfficeId = data.add( (Mappable) headOffice, "julie" );
   data.tag( headOfficeId, "work" );

8. Define two more locations, and invoke add() to add the locations to MapDataModel. Invoke tag() to assign the appropriate tags for the locations.

   MapLocation paulHome = new MapLocation( 43.49487, -80.55335, 
           "Paul - Home", null );
   int paulHomeId = data.add( (Mappable) paulHome, "paul" );
   data.tag( paulHomeId, "home" );
   data.tag( headOfficeId, "paul" );
            
   data.tag( paulHomeId, "sarah" );
   MapLocation manufacturing = new MapLocation( 43.46514, -80.50506, 
           "Manufacturing", null );
   int manufacturingId = data.add( (Mappable) manufacturing, "sarah" );
   data.tag( manufacturingId, "work" );

9. Turn on visibility for the locations that have the “work” tag. By default, all the locations are visible on the map. Invoke setVisibleNone() to turn the visibility off for all the locations. Invoke setVisible() and pass the "work" tag as an argument to specify that only the locations with the “work” tag are visible on the map.

   data.setVisibleNone();
   data.setVisible( "work" );

10. Invoke getMapField().update() to update the map view. Pass the Boolean value true to the update method to recalculate the center and zoom level of the map with the visible locations on the map.

    map.getMapField().update(true);