null pointer exception from getMyLocation()

spargonaut · by **spargonaut** » Thu Apr 29, 2010 6:19 pm

hello everyone.

I'm trying to create a simple mapActivity that only places a little android over a particular coordinate and animates the map to that point. I've determined that I'm getting a null pointer exception whenever i try to execute the line:

mapController.animateTo( mMyLocationOverlay.getMyLocation() );

the above line is within a try/catch block and I used the eclipse debugger to nail down where I'm getting that error from. I'm testing this on my actual phone so ( I'm assuming ) I don't need to create mock locations. If i'm wrong about that, please correct me.

In my manifest I have the lines:

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_LOCATION" />
<uses-permission android:name="android.permission.ACCESS_GPS" />

here is my code if you would like to have a look. if it matters, I'm following the example laid out in the MJAndroid project that is described in O'Reilly's "Android Application Development" book.

I'm new to android development, so if you see any bad habits or have any other constructive suggestions, please feel free to speak up.

thanks
spargonaut

Syntax: [ Download ] [ Hide ]

Using java Syntax Highlighting

 
package org.spargonaut.and.MapsActivity;
 
// imports for use with google maps api
 
import com.google.android.maps.MapActivity;
 
import com.google.android.maps.MapView;
 
import com.google.android.maps.MyLocationOverlay;
 
import com.google.android.maps.MapController;
 
// imports for graphics
 
import android.graphics.drawable.Drawable;
 
import com.google.android.maps.ItemizedOverlay;
 
import com.google.android.maps.GeoPoint;
 
import com.google.android.maps.OverlayItem;
 
// for logging purposes
 
import android.util.Log;
 
// autocreated imports
 
import android.app.Activity;
 
import android.os.Bundle;
 
public class MapsActivity extends MapActivity {
 
        /** global class members */
 
        MapView mvMap;
 
        MyLocationOverlay mMyLocationOverlay;
 
        // testing
 
        int lat1 = 1;
 
        int lon1 = 1;
 
        GeoPoint geod = new GeoPoint( lat1, lon1 );
 
        long testLat = 0;
 
    /** Called when the activity is first created. */
 
    @Override
 
    public void onCreate(Bundle savedInstanceState) {
 
        super.onCreate(savedInstanceState);
 
        setContentView(R.layout.main);
 
        // hmm, lets get some sort of mapview
 
        mvMap = ( MapView ) findViewById( R.id.mapmain );
 
        // get the controller
 
        final MapController mapController = mvMap.getController();
 
        // testing
 
        testLat = geod.getLatitudeE6();
 
        // lets add an overlay shall we?
 
        mMyLocationOverlay = new MyLocationOverlay( this, mvMap );
 
        mMyLocationOverlay.enableMyLocation();
 
        // testing
 
//        geod = mMyLocationOverlay.getMyLocation();
 
//        testLat = geod.getLatitudeE6();
 
        mMyLocationOverlay.runOnFirstFix( 
 
                        new Runnable() {
 
                                public void run() {
 
                                        mapController.animateTo( mMyLocationOverlay.getMyLocation() );
 
                                        // testing
 
//                                      mapController.animateTo( new GeoPoint( 32748131, -96826517 ) );
 
                                        mapController.setZoom( 16 );
 
                                }
 
                        } );
 
        // testing
 
      geod = mMyLocationOverlay.getMyLocation();
 
//      testLat = geod.getLatitudeE6();
 
        // create an icon to use on the map
 
        Drawable marker = getResources().getDrawable( R.drawable.android_tiny_image );
 
        marker.setBounds( 0, 0, marker.getIntrinsicWidth(), marker.getIntrinsicHeight() );
 
        mvMap.getOverlays().add( new TestMapOverlay( marker ) );
 
        mvMap.setClickable( true );
 
        mvMap.setEnabled( true );
 
        mvMap.setSatellite( false );
 
        mvMap.setTraffic( false );
 
        mvMap.setStreetView( false );
 
        // start out with a general zoom
 
        mapController.setZoom( 16 );
 
        mvMap.invalidate();
 
        // testing
 
                int lat1 = 32867727;
 
                int lon1 = -96770478;
 
        // lets try to head over to my location
 
        try {
 
                // testing
 
//              mapController.animateTo( new GeoPoint( lat1, lon1 ) );
 
                mapController.animateTo( mMyLocationOverlay.getMyLocation() );
 
        } catch( Exception e ) {
 
                Log.i( "maptest1", "unable to goto my location:->" + e);
 
        }
 
    } // end onCreate()
 
    // to make the compiler shut up
 
    @Override
 
    public boolean isRouteDisplayed() { return false; }
 
    /* overlay stuff
 
     * this class is mainly stolen verbatim from MJAndroid.Microjobs.java
 
     */
 
    private class TestMapOverlay extends ItemizedOverlay< OverlayItem > {
 
        // marker the push-pin
 
        public TestMapOverlay( Drawable marker ) {
 
                super( marker );
 
                populate();
 
        } // end constructor
 
        /* see com.google.android.maps.ItemizedOverlay#size()
 
         */
 
        @Override
 
        public int size() {
 
                int size = 1;
 
                return size;
 
        }
 
        /* see com.google.android.maps.ItemizedOverlay#createItem( int )
 
         */
 
        @Override
 
        protected OverlayItem createItem( int i ) {
 
                //JobDetailCurser c = db.getJobDetails( i + 1 );
 
                //String contactName = c.getColContactName();
 
                //String description = c.getCOlDescription();
 
                //int lat = ( int ) c.getColLatitude();
 
                //int lon = ( int ) c.getLongitude();
 
                String contactName = "Contact: spargo";
 
                String description = "spargo's test description";
 
                // test location
 
//              int lat = 32748131;
 
//              int lon = -96826517;
 
                int lat = 32867727;
 
                int lon = -96770478;
 
                // northpark
 
                return new OverlayItem( new GeoPoint( lat, lon ), contactName, description );
 
        }
 
        /* MicroJobs has an onTap method that probably should be implemented,
 
         * but I'm not going to implement it at the moment
 
         * I prolly should just to learn wtf it does
 
         */
 
    } // end class TestMapOverlay()
 
} // end class MapsActivity()
 
Parsed in 0.048 seconds,  using GeSHi 1.0.8.4

also, if you look at the following line in the debugger ( the one after mMyLocationOverlay.runOnFirstFix() ):

// testing
geod = mMyLocationOverlay.getMyLocation();

you'll see that getMyLocation returns null.

kekomal · by **kekomal** » Thu Apr 29, 2010 10:07 pm

Try...

mvMap.getOverlays().add(mMyLocationOverlay);

...before any...

mMyLocationOverlay.getMyLocation()

spargonaut · by **spargonaut** » Thu Apr 29, 2010 10:28 pm

werd!

thanks for the suggestion! I've been racking my brain over this for the past few days. as soon as i have the chance i'll try it out and let you know how it works.

do I only need to do this once, or should it be done every time i call *.getMyLocation()?

spargonaut · by **spargonaut** » Thu Apr 29, 2010 10:56 pm

unfortunately, its still doing it ( returning null from mvMyLocationOverlay.getMyLocation() ).

I tried it in two places...

first below this line:
mMyLocationOverlay.enableMyLocation();

and above this line:
// testing
geod = mMyLocationOverlay.getMyLocation();

so that it reads:

Syntax: [ Download ] [ Hide ]

Using java Syntax Highlighting

 
mMyLocationOverlay.enableMyLocation();
 
mvMap.getOverlays().add( mMyLocationOverlay );
 
           // testing
 
//        geod = mMyLocationOverlay.getMyLocation(); 
 
Parsed in 0.031 seconds,  using GeSHi 1.0.8.4

and the second time just before the try/catch block so that it reads...

Syntax: [ Download ] [ Hide ]

Using java Syntax Highlighting

 
//              int lat1 = 32.867727;
 
//              int lon1 = -96.770478;
 
        // addev suggestion 1 - kekomal
 
      mvMap.getOverlays().add( mMyLocationOverlay );
 
      geod = mMyLocationOverlay.getMyLocation();
 
        // lets try to head over to my location
 
        try {
 
                // testing
 
//              mapController.animateTo( new GeoPoint( lat1, lon1 ) );
 
                mapController.animateTo( mMyLocationOverlay.getMyLocation() );
 
        } catch( Exception e ) {
 
                Log.i( "maptest1", "unable to goto my location:->" + e);
 
        }
 
Parsed in 0.035 seconds,  using GeSHi 1.0.8.4

both times, geod is showing as null in the debugger and the map that is pulling up is nowhere near where it should be.

thanks for the suggestion though. I'm open to trying others if you or anyone else has them.

kekomal · by **kekomal** » Thu Apr 29, 2010 11:27 pm

My suggestion was only needed to be done once (after the enableMyLocation would be a good place).

Try including also the permission android.permission.ACCESS_FINE_LOCATION. Test the mMyLocationOverlay.getMyLocation() inside the Runnable before the others.

spargonaut · by **spargonaut** » Thu Apr 29, 2010 11:50 pm

Added the permission you suggested.
and added the line you suggested after the first instance of mMyLocationOverlay.enableMyLocation() and uncommented the line that reads: geod = mMyLocationOverlay.getMyLocation();
and its still returning null.

Also, I tried putting a breakpoint within the runnable() but eclipse seemed to just jump right over it.

I'm noticing in LogCat the line:
04-29 11:37:33.220: ERROR/AndroidRuntime(122): ERROR: thread attach failed

not sure if that helps, but i get the feeling that for some reason the runnable isn't executing properly.

anything else to try?

thanks again!

spargonaut · by **spargonaut** » Fri Apr 30, 2010 12:06 am

wait wait wait wait!!!

I take that back. its actually working!
its taking a while, but its working!!!

well, geod is still resolving to null in the debugger, but when i run the application without the debugger, it actually puts a little blue dot over my location and puts my little android dude next to it.

thanks a ton!

have a great day or night or whatever time it is where you are!

( although, upon further reflection, I wonder if it was adding the permission, the *.add() method or both that got it to work )

thoughts?

null pointer exception from getMyLocation()

null pointer exception from getMyLocation()

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