CODEWITHSUNDEEP
androidnullpointerexceptionandroid-activitylocationmanagerandroid-location
vamsiampolu
vamsiampolu

Reputation: 6622

LocationManager is null after initialization

I have tried to initialize the LocationManager and use a Button to get the location obtained as a Toast on the screen,however I find that the LocationManager is null:

/MyLocationTest﹕ Failed to initialize LocationManager

java.lang.NullPointerException
        at com.example.mylocationtest.MainActivity$1.onClick(MainActivity.java:46)
        at android.view.View.performClick(View.java:4240)
        at android.view.View$PerformClick.run(View.java:17721)
        at android.os.Handler.handleCallback(Handler.java:730)
        at android.os.Handler.dispatchMessage(Handler.java:92)
        at android.os.Looper.loop(Looper.java:137)
        at android.app.ActivityThread.main(ActivityThread.java:5103)
        at java.lang.reflect.Method.invokeNative(Native Method)
        at java.lang.reflect.Method.invoke(Method.java:525)
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:737)
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553)
        at dalvik.system.NativeStart.main(Native Method)

The first line is a message that I print to Logcat because the LocationManager is null even though I initialize it like this in onCreate:

  locMan=(LocationManager)this.getSystemService(Context.LOCATION_SERVICE);
  //set a click listener for the button:
  btn_loc.setOnClickListener(new View.OnClickListener(){
    @Override
    public void onClick(View v)
    {
       boolean isGPSReady,isNetworkReady;
       if(locMan==null)
       {
          Log.d("MyLocationTest", "Failed to initialize LocationManager");
       }
       isGPSReady=locMan.isProviderEnabled(LocationManager.GPS_PROVIDER);
       isNetworkReady=locMan.isProviderEnabled(LocationManager.NETWORK_PROVIDER);
       if(!isNetworkReady && !isGPSReady)
       {
         Toast.makeText(getBaseContext(),"Sorry,location could not be enabled",Toast.LENGTH_SHORT).show();
       }
       else if(isNetworkReady)
       {
        //the third parameter is a looper that controls where the callback happens from...
              locMan.requestSingleUpdate(LocationManager.NETWORK_PROVIDER,locEar_network, null);
        latitude=loc.getLatitude();
        longitude=loc.getLongitude();
        Toast.makeText(getBaseContext(),"The latitude is "+latitude+" and the longitude is "+longitude+" and the accuracy is "+loc.getAccuracy(),Toast.LENGTH_SHORT).show();
       }
       else if(isGPSReady)
       {
           locMan.requestSingleUpdate(LocationManager.GPS_PROVIDER,locEar_gps,null);
           latitude=loc.getLatitude();
           longitude=loc.getLongitude();
           Toast.makeText(getBaseContext(),"The latitude is "+latitude+" and the longitude is "+longitude+ "and the accuracy is "+loc.getAccuracy(),Toast.LENGTH_SHORT).show();
       }

     }
  });

In my manifest,I have used the following to ensure that API level 9 is the minSDKVersion for requestSingleUpdate and the app is permitted access to fine location:

  <manifest xmlns:android="http://schemas.android.com/apk/res/android"
package="com.example.mylocationtest" >m
<uses-sdk android:minSdkVersion="9"
          android:targetSdkVersion="18"/>

<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION"/>

EDIT:

The entire class is here as a pastebin

How can I ensure that the LocationManager is never null?

Upvotes: 2

Views: 2352

Answers (2)

Rakhita Wickramatunge
Rakhita Wickramatunge

Reputation: 4503

You are only setting up a log if the LocationManager is null. You should avoid accessing it when it's null also. Modify you code like this.

   boolean isGPSReady,isNetworkReady;
   if(locMan==null)
   {
      Log.d("MyLocationTest", "Failed to initialize LocationManager");
   }
   else{
       isGPSReady=locMan.isProviderEnabled(LocationManager.GPS_PROVIDER);
       isNetworkReady=locMan.isProviderEnabled(LocationManager.NETWORK_PROVIDER);

       if(!isNetworkReady && !isGPSReady)
       {
            Toast.makeText(getBaseContext(),"Sorry,location could not be enabled",Toast.LENGTH_SHORT).show();
       }
       else if(isNetworkReady)
       {
            //the third parameter is a looper that controls where the callback happens from...
            locMan.requestSingleUpdate(LocationManager.NETWORK_PROVIDER,locEar_network, null);
            latitude=loc.getLatitude();
            longitude=loc.getLongitude();
            Toast.makeText(getBaseContext(),"The latitude is "+latitude+" and the longitude is "+longitude+" and the accuracy is "+loc.getAccuracy(),Toast.LENGTH_SHORT).show();
       }
       else if(isGPSReady)
       {
           locMan.requestSingleUpdate(LocationManager.GPS_PROVIDER,locEar_gps,null);
           latitude=loc.getLatitude();
           longitude=loc.getLongitude();
           Toast.makeText(getBaseContext(),"The latitude is "+latitude+" and the longitude is "+longitude+ "and the accuracy is "+loc.getAccuracy(),Toast.LENGTH_SHORT).show();
       }
   }

One more thing, are you using a GPS enabled device to test this? If you want more information refer this.

Try adding these two permissions also to AndroidManifest.xml file.

INTERNET

ACCESS_COARSE_LOCATION

Upvotes: 1

Abx
Abx

Reputation: 2882

If Location manager tries to get a location from the network provider, some times there might not be a location available from the network provider or it may require some time to get the location in these cases you might get a null.

Location manager might also get null if the gps coudnt find any location most probably inside a building

Upvotes: 1

Related Questions