Runtime Exception unable to start MainActivity

I'm trying to test my Android app on a new phone I've just purchased with Android 4.2. It runs every other app I test, and this particular app also works on other devices. When I try to run the code it's giving me the following errors:

> 02-23 12:15:08.532: E/AndroidRuntime(5431): FATAL EXCEPTION: main
02-23 12:15:08.532: E/AndroidRuntime(5431): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.antiquity/com.example.antiquity.MainActivity}: java.lang.NullPointerException
02-23 12:15:08.532: E/AndroidRuntime(5431):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2343)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2395)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at android.app.ActivityThread.access$600(ActivityThread.java:162)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1364)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at android.os.Handler.dispatchMessage(Handler.java:107)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at android.os.Looper.loop(Looper.java:194)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at android.app.ActivityThread.main(ActivityThread.java:5371)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at java.lang.reflect.Method.invokeNative(Native Method)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at java.lang.reflect.Method.invoke(Method.java:525)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:833)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:600)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at dalvik.system.NativeStart.main(Native Method)
02-23 12:15:08.532: E/AndroidRuntime(5431): Caused by: java.lang.NullPointerException
02-23 12:15:08.532: E/AndroidRuntime(5431):     at com.example.antiquity.MainActivity.setUpLocation(MainActivity.java:127)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at com.example.antiquity.MainActivity.onCreate(MainActivity.java:96)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at android.app.Activity.performCreate(Activity.java:5139)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1084)
02-23 12:15:08.532: E/AndroidRuntime(5431):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2307)
02-23 12:15:08.532: E/AndroidRuntime(5431):     ... 11 more

Now I've checked line 127 and even removing that and leaving an empty line will still cause this error relating to line 127.

My MainActivity.class code:

public class MainActivity extends Activity {

    private GoogleMap map;
    Intent data;    
    MonumentsDatabase monDatabase;
    int _id;
    int _lat;
    int _lng;
    String _title;
    LatLng MARKERS;
    LocationManager locationManager;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();

        map.setOnInfoWindowClickListener(new OnInfoWindowClickListener() {
            @Override
            public void onInfoWindowClick(Marker marker) {
               Intent data = new Intent(MainActivity.this, DisplayData.class);
               startActivity(data);

            }
        });

        setUpLocation();

        locationManager = (LocationManager) getSystemService( Context.LOCATION_SERVICE );

        if ( !locationManager.isProviderEnabled( LocationManager.GPS_PROVIDER ) ) {
            disabledGPS();
        }       

        map.setMyLocationEnabled(true);
    }


    public void setUpLocation() {
        locationManager = (LocationManager) getSystemService(LOCATION_SERVICE);     
        Criteria criteria = new Criteria();      
        String provider = locationManager.getBestProvider(criteria, true);
        Location myLocation = locationManager.getLastKnownLocation(provider);
        double latitude = myLocation.getLatitude();
        double longitude = myLocation.getLongitude();
        LatLng latLng = new LatLng(latitude, longitude);      
        map.moveCamera(CameraUpdateFactory.newLatLng(latLng));
        map.animateCamera(CameraUpdateFactory.zoomTo(40));      
    }


    private void disabledGPS() {
        final AlertDialog.Builder gpsDisabled = new AlertDialog.Builder(this);
        gpsDisabled.setMessage("This app requires GPS to be enabled. Do you wish to continue?")
            .setCancelable(false)
            .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    startActivity(new Intent(android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS));
                }
            })
            .setNegativeButton("No", new DialogInterface.OnClickListener() {
                public void onClick(DialogInterface dialog, int id) {
                    dialog.cancel();
                }
            });
        AlertDialog mainAlert = gpsDisabled.create();
        mainAlert.show();
    }

    /**
    public boolean onMarkerClick(Marker marker) {
        //Intent data = new Intent(this, DisplayData.class);
        // TODO Auto-generated method stub
        startActivity(data);
        return true;
    }
    */

    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        // Inflate the menu; this adds items to the action bar if it is present.
        getMenuInflater().inflate(R.menu.main, menu);
        return true;
    }

    public void createDatabase() {
        monDatabase = new MonumentsDatabase(this);
        try {   
            monDatabase.createDatabase();
        } catch (IOException ioe) {
            throw new Error("Unable to create database");
        }
        try {
            monDatabase.openDatabase();
        }catch(SQLException sqle){ 
            throw sqle;
        }
    }

}

I find it strange how it works on one device and then crashes on another.

Thanks for any help! :)

EDIT:

activity_layout.xml file:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="fill_parent"

tools:context=".MainActivity" >

<fragment
    android:id="@+id/map"
    android:name="com.google.android.gms.maps.MapFragment"
    android:layout_width="match_parent"
    android:layout_height="match_parent" />

AndroidManifest.xml file:

Not sure why, but it isn't liking the indents.

So sorry for the link but:

http://pastebin.com/kd4EpP4W

NullPointerException

I think your

 Location myLocation = locationManager.getLastKnownLocation(provider);

line returning null.

Please check this answer. It might be helpful

M D

Here, If you are targeting your minimum SDK version < 12 in your manifest file then you can't use MapFragment. So must be sure that your minimum SDK version is above or equals to 12. And if it is not then change in your xml file from

android:name="com.google.android.gms.maps.MapFragment"

android:name="com.google.android.gms.maps.SupportMapFragment"

And also in your activity change from

 map = ((MapFragment) getFragmentManager().findFragmentById(R.id.map)).getMap();

 map=((SupportMapFragment)getSupportFragmentManager().findFragmentById(R.id.map)).getMap();

And also If you're using fragments on older devices (pre Honeycomb) you should always extend your Activity from FragmentActivity.

Also import android.support.v4.app.FragmentActivity and for more information on this go to my this answer

If I don't mistake, fragments should be used in Activity which extends either Fragment or FragmentActivity. Probably something is wrong with map

来源：https://stackoverflow.com/questions/21968077/runtime-exception-unable-to-start-mainactivity

标签

java

android

eclipse

exception

runtime