Revision as of 05:26, 7 August 2012

This article explains how to add different types of content to the Map when using Maps API for Java ME API. Removing content and other content functionality is also dealt with in this article.

Introduction

The Maps API for Java ME makes it possible to easily embed the Nokia Maps service into Java ME applications.

MapMarkers have already been discussed in the Adding Markers to the Map with Maps API for Java ME article, thus this article will concentrate on other types of content that may be added to the map.

Adding content to the map

In addition to MapMarkers the following content types have class definition included with the Java ME Maps API:

• Polygon,
• Polyline,
• Circle, and
• Rectangle

Polylines can be constructed by using the MapFactory, the constructor takes only one argument, which is an array of points for the Polyline. after construction you can use the methods provide by the MapPolyline class to modify it, for example you can change the color of the line with setColor() method.

GeoCoordinate[] polylinCoord = new GeoCoordinate[4];
polylinCoord[0] = new GeoCoordinate(60.27, 24.81, 0);
polylinCoord[1] = new GeoCoordinate(60.35, 24.70, 0);
polylinCoord[2] = new GeoCoordinate(60.19, 24.57, 0);
polylinCoord[3] = new GeoCoordinate(60.27, 24.81, 0);
 
MapPolyline polyline = mapCanvas.getMapFactory().createMapPolyline(polylinCoord);
polyline.setColor(0xFF43A5FF);
 
mapCanvas.getMapDisplay().addMapObject(polyline)

In a similar manner to Polylines, Polygons are constructed via the MapFactory, and the constructor also takes the array of points:

GeoCoordinate[] polygonCoord = new GeoCoordinate[3];
polygonCoord[0] = new GeoCoordinate(60.22, 24.81, 0);
polygonCoord[1] = new GeoCoordinate(60.30, 24.70, 0);
polygonCoord[2] = new GeoCoordinate(60.14, 24.57, 0);                      
 
MapPolygon polygon = mapCanvas.getMapFactory().createMapPolygon(polygonCoord);
polygon.setColor(0xAA43A51B);
 
mapCanvas.getMapDisplay().addMapObject(polygon);

The Circle and rectangle are basically special polygons helper classes. For the Circle the constructor takes two arguments, which are the radius and center. And for the Rectangle the only argument taken is bounding box for the rectangle, which is basically area defined by two points, left top point and the bottom right point.

MapCircle myCircle = mapCanvas.getMapFactory().createMapCircle(5000.0,new GeoCoordinate(60.30, 24.70,0));
// ...
GeoBoundingBox rectnaglebox = new GeoBoundingBox(new GeoCoordinate(60.35, 24.60,0), new GeoCoordinate(60.25, 24.80,0));
MapRectangle rectnagle = mapCanvas.getMapFactory().createMapRectangle(rectnaglebox);

Z-ordering content

The Z-ordering content is handled simply by using the setzIndex() method for each content that needs to be ordered. Giving a lower value in setzIndex() will make the content to be drawn under the content that has higher values. For example if you want myCircle to be drawn on top of the rectangle, you can do it with following code:

int markerZ = 1;
int polyZ = 0;
myCircle.setzIndex(markerZ);
rectangle.setzIndex(polyZ);

Hiding content without deleting them

Each content item can be hidden by calling the setVisible() method with a Boolean argument set to false :

boolean vissible = !rectnagle.isVisible();
rectnagle.setVisible(vissible);

Removing content

Each content added to the Map display with the addMapObject() method can be also removed by using the removeMapObject() method.

mapCanvas.getMapDisplay().addMapObject( myCircle );

Thus, if for example, myCircle is added with the code above, it can be later on removed from the Map by using the code shown below.

mapCanvas.getMapDisplay().removeMapObject(myCircle);

Resources

Full source code illustrating usage for map content types discussed in this article is available at: File:Java MapContent.zip

Summary

The Maps API for Java ME offers rich functionality which facilitates the integration of all the main Nokia Maps features into a Java ME application, with just a few lines of code.