Question

i am trying a develop a application..following is a snippet

class metro_nodes {
public String station;
public GeoPoint point; }

public class mainscreen extends MapActivity {
/** Called when the activity is first created. */

MapController controller;
double latitude,longitude;
LocationManager loc;
Location lastknownloc;
LocationListener loclistener;
List<GeoPoint> geopoints = new ArrayList<GeoPoint>();
MapView mapView;
private LinkedList<metro_nodes> station_location = new LinkedList<metro_nodes>();
metro_nodes anand_nagar;
anand_nagar.station = "anand_nagar";
    }

now in the second last line its giving -“Syntax error on token “station”, VariableDeclaratorId expected after this token”

if i put curly braces around this statement then error get removed..but then i get java lang null pointer exception…
whats the problm ??

Answer 1

You haven’t posted the code that gives you the syntax error…but I’m guessing you’re getting the null pointer exception because you never initialized any “metro_nodes” objects.

For example:

// This is a helper class
class MetroNode {
  public String station;
  public GeoPoint point; 

  public MetroNode (String station, GeoPoint point) {
    this.station = station;
    this.point = point;
  }
}

// This is the module's main class
public class MainScreen extends MapActivity {

  // This is public and private data for each class instance
  private LinkedList<MetroNode> station_location = null;

  // This is the activity's initialization
  public void onCreate(Bundle savedInstanceState) 
    station_locations = new LinkedList<MetroNode>();
    MetroNode metroNode = new MetroNode ("anand_nagar", new GeoPoint (1.00, 2.00));
    station_locations.add (metroNode);
  ...