I am a newbie to Android. I have developed an app in which I am required to track a user's location using either gps, internet or using cellid.I am using 2 Activities
(MainActivity
and SavelocationsActivity implements LocationListener
),a Service(Ser)
and a Broadcast Receiver(k)
.
When I click a Button
in the MainActivity
it was required to go to SaveLocationsActivity
. I used to get that a few days before but now the lattitude
and longitude
values have become null
and I am getting the following errors i.e:
null pointer exception.
As I am a newbie please explain me what to do and where I am going wrong step by step.Thank you in advance. I am posting the code and error log below.
SaveLocationsActivity
public class SaveLocationsActivity extends Activity implements LocationListener{
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.savelocations);
locationManager = (LocationManager)this.getSystemService(LOCATION_SERVICE);
isNetworkEnabled = locationManager
.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
//Toast.makeText(this,"in activity"+isNetworkEnabled ,Toast.LENGTH_LONG).show();
isGPSEnabled = locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER);
if(isNetworkEnabled==true && isGPSEnabled==false)
{
getLocation(LocationManager.NETWORK_PROVIDER);
}
else if(isGPSEnabled==true && isNetworkEnabled==false)
{
getLocation(LocationManager.GPS_PROVIDER);
}
else if(isGPSEnabled==true && isNetworkEnabled==true )
{
getLocation(LocationManager.GPS_PROVIDER);
}
private Location getLocation(String provider) {
// TODO Auto-generated method stub
if (locationManager.isProviderEnabled(provider)) {
locationManager.requestLocationUpdates(provider,
6000, 10, this);
if (locationManager != null) {
location = locationManager.getLastKnownLocation(provider);
double latitude = location.getLatitude();
double longitude = location.getLongitude();
final String t5 = String.valueOf(latitude);
final String t6 = String.valueOf(longitude);
e5.setText(t5);
e6.setText(t6);
savelocation.put("t5",t5);
savelocation.put("t6",t6);
return location;
}
}
return location;
}
@Override
public void onLocationChanged(Location l) {
// TODO Auto-generated method stub
double latitude = l.getLatitude();
double longitude = l.getLongitude();
final String t5 = String.valueOf(latitude);
final String t6 = String.valueOf(longitude);
//Toast.makeText(SaveLocationsActivity.this,""+t5,Toast.LENGTH_LONG).show();
e5.setText(t5);
e6.setText(t6);
}
Error logs:
03-21 23:34:50.309: E/AndroidRuntime(15368): FATAL EXCEPTION: main
03-21 23:34:50.309: E/AndroidRuntime(15368): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.broadcast/com.example.broadcast.SaveLocationsActivity}: java.lang.NullPointerException
03-21 23:34:50.309: E/AndroidRuntime(15368): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2114)
03-21 23:34:50.309: E/AndroidRuntime(15368): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2139)
03-21 23:34:50.309: E/AndroidRuntime(15368): at android.app.ActivityThread.access$700(ActivityThread.java:143)
03-21 23:34:50.309: E/AndroidRuntime(15368): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1241)
03-21 23:34:50.309: E/AndroidRuntime(15368): at android.os.Handler.dispatchMessage(Handler.java:99)
03-21 23:34:50.309: E/AndroidRuntime(15368): at android.os.Looper.loop(Looper.java:137)
03-21 23:34:50.309: E/AndroidRuntime(15368): at android.app.ActivityThread.main(ActivityThread.java:4960)
03-21 23:34:50.309: E/AndroidRuntime(15368): at java.lang.reflect.Method.invokeNative(Native Method)
03-21 23:34:50.309: E/AndroidRuntime(15368): at java.lang.reflect.Method.invoke(Method.java:511)
03-21 23:34:50.309: E/AndroidRuntime(15368): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1038)
03-21 23:34:50.309: E/AndroidRuntime(15368): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:805)
03-21 23:34:50.309: E/AndroidRuntime(15368): at dalvik.system.NativeStart.main(Native Method)
03-21 23:34:50.309: E/AndroidRuntime(15368): Caused by: java.lang.NullPointerException
03-21 23:34:50.309: E/AndroidRuntime(15368): at com.example.broadcast.SaveLocationsActivity.getLocation(SaveLocationsActivity.java:209)
03-21 23:34:50.309: E/AndroidRuntime(15368): at com.example.broadcast.SaveLocationsActivity.onCreate(SaveLocationsActivity.java:100)
03-21 23:34:50.309: E/AndroidRuntime(15368): at android.app.Activity.performCreate(Activity.java:5203)
03-21 23:34:50.309: E/AndroidRuntime(15368): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1094)
03-21 23:34:50.309: E/AndroidRuntime(15368): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2078)
03-21 23:34:50.309: E/AndroidRuntime(15368): ... 11 more
In the method getLocation()
the problem is probably here:
if (locationManager != null) {
location = locationManager.getLastKnownLocation(provider);
double latitude = location.getLatitude();
double longitude = location.getLongitude();
because getLastKnownLocation
can return null
if the previous location is unknown. So by calling location.getLatitude()
you incur in a NullPointerException
.
To avoid this you can check the returned value for null
like:
if (locationManager != null) {
location = locationManager.getLastKnownLocation(provider);
if(location!=null)
//...etc...