Starting my android app when GPS is enabled force closes

Question

Can anyone offer an insight into my problem please?

My app works when GPS is disabled, but FC's when starting while GPS is enabled. On a cold start it offers the option to turn on the GPS. After doing that, pressing the back arrow button it returns to the app activity (although the GPS icon is not visible in the status bar, on a side note, how do I get it to display here?).

I exit the application by pressing the back button or using the menu option whilst GPS is still on. Now, when I try to start the app, it FC's. The blinking GPS icon appears behind the FC message and disappears when I acknowledge the FC.

Here is the code:

@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    getLocation();
    setupWebView();
    this.setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
}

private void setupWebView() {
    final String centerURL = "javascript:centerAt("
        + mostRecentLocation.getLatitude() + ","
        + mostRecentLocation.getLongitude() + ")";
    webView = (WebView) findViewById(R.id.webview);
    // Get rid of white line on the right
    webView.setScrollBarStyle(View.SCROLLBARS_INSIDE_OVERLAY);
    webView.getSettings().setJavaScriptEnabled(true);
    // Wait for the page to load then send the location information
    webView.setWebViewClient(new WebViewClient() {

        @Override
        public void onPageFinished(WebView view, String url) {
            webView.loadUrl(centerURL);
        }
    });
    webView.loadUrl(MAP_URL);
}

/**
 * The Location Manager manages location providers. This code searches for
 * the best provider of data (GPS, WiFi/cell phone tower lookup, some other
 * mechanism) and finds the last known location.
 **/
private void getLocation() {
    locationManager = (LocationManager) 
            getSystemService(Context.LOCATION_SERVICE);
    if (!locationManager.isProviderEnabled(LocationManager.GPS_PROVIDER)) {
        createGpsDisabledAlert();
    }
    Criteria criteria = new Criteria();
    criteria.setAccuracy(Criteria.ACCURACY_FINE);
    provider = locationManager.getBestProvider(criteria, true);
    // In order to make sure the device is getting location, request
    // updates. Look to tweaking the arguments to this for a smooth ride
    locationManager.requestLocationUpdates(provider, 1, 0, this);
    mostRecentLocation = locationManager.getLastKnownLocation(provider);
}

private void createGpsDisabledAlert() {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setMessage("Your GPS is disabled! Would you like to enable it?")
            .setCancelable(false)
            .setPositiveButton("Enable GPS",
                    new DialogInterface.OnClickListener() {

                        public void onClick(DialogInterface dialog, int id) {
                            showGpsOptions();
                        }
                    });
    builder.setNegativeButton("Use Wifi or 3g for location",
            new DialogInterface.OnClickListener() {

                public void onClick(DialogInterface dialog, int id) {
                    dialog.cancel();
                }
            });
    AlertDialog alert = builder.create();
    alert.show();
}

private void showGpsOptions() {
    Intent gpsOptionsIntent = new Intent(
            android.provider.Settings.ACTION_LOCATION_SOURCE_SETTINGS);
    startActivity(gpsOptionsIntent);
}

// Menu setup
@Override
public boolean onCreateOptionsMenu(Menu menu) {
    menu.add(0, 0, 0, R.string.close).setIcon(
            android.R.drawable.ic_menu_close_clear_cancel);
    return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch (item.getItemId()) {
    case 0:
        super.onStop();
        super.onDestroy();
        this.finish();
        return true;
    default:
        return super.onOptionsItemSelected(item);
    }
}

@Override
protected void onResume() {
    locationManager.requestLocationUpdates(provider, 1, 0, this);
    super.onResume();
}

@Override
protected void onPause() {
    locationManager.removeUpdates(this);
    super.onPause();
}

/** Sets the mostRecentLocation object to the current location of the device **/
public void onLocationChanged(Location location) {
    mostRecentLocation = location;
    final String centerURL = "javascript:centerAt("
        + mostRecentLocation.getLatitude() + ","
        + mostRecentLocation.getLongitude() + ")";
    // This line is good to update the map with the current location
    webView.loadUrl(centerURL);
}

and this is the logcat from eclipse:

11-04 11:45:10.774: INFO/ActivityManager(52): Starting activity: Intent { act=android.intent.action.MAIN cat=[android.intent.category.LAUNCHER] flg=0x10000000 cmp=com.weuni.android.mups/.ViewCampusActivity }
11-04 11:45:10.925: INFO/ActivityManager(52): Start proc com.weuni.android.mups for activity com.weuni.android.mups/.ViewCampusActivity: pid=225 uid=10030 gids={3003, 1015}
11-04 11:45:10.934: DEBUG/AndroidRuntime(197): Shutting down VM
11-04 11:45:10.944: DEBUG/dalvikvm(197): DestroyJavaVM waiting for non-daemon threads to exit
11-04 11:45:10.954: DEBUG/dalvikvm(197): DestroyJavaVM shutting VM down
11-04 11:45:10.954: DEBUG/dalvikvm(197): HeapWorker thread shutting down
11-04 11:45:10.954: DEBUG/dalvikvm(197): HeapWorker thread has shut down
11-04 11:45:10.954: DEBUG/jdwp(197): JDWP shutting down net...
11-04 11:45:10.964: INFO/jdwp(197): adbd disconnected
11-04 11:45:10.974: DEBUG/dalvikvm(197): VM cleaning up
11-04 11:45:11.055: ERROR/AndroidRuntime(197): ERROR: thread attach failed
11-04 11:45:11.185: DEBUG/dalvikvm(197): LinearAlloc 0x0 used 636388 of 5242880 (12%)
11-04 11:45:11.485: DEBUG/ddm-heap(209): Got feature list request
11-04 11:45:11.555: DEBUG/NetworkLocationService(52): onCreate
11-04 11:45:11.555: DEBUG/ddm-heap(225): Got feature list request
11-04 11:45:11.595: DEBUG/LocationManager(52): Constructor: service = com.android.server.LocationManagerService@43ceb720
11-04 11:45:11.625: ERROR/ActivityThread(52): Failed to find provider info for com.google.settings
11-04 11:45:11.625: ERROR/ActivityThread(52): Failed to find provider info for com.google.settings
11-04 11:45:11.934: INFO/ARMAssembler(52): generated scanline__00000177:03515104_00000001_00000000 [ 73 ipp] (95 ins) at [0x45ef00:0x45f07c] in 1428001 ns
11-04 11:45:12.004: INFO/ARMAssembler(52): generated scanline__00000077:03545404_00000004_00000000 [ 47 ipp] (67 ins) at [0x33bf28:0x33c034] in 772000 ns
11-04 11:45:12.185: WARN/WindowManager(52): No window to dispatch pointer action 0
11-04 11:45:12.195: WARN/WindowManager(52): No window to dispatch pointer action 1
11-04 11:45:12.724: DEBUG/LocationManager(225): Constructor: service = android.location.ILocationManager$Stub$Proxy@43d14648
11-04 11:45:12.794: DEBUG/GpsLocationProvider(52): setMinTime 1
11-04 11:45:12.794: DEBUG/GpsLocationProvider(52): startNavigating
11-04 11:45:12.834: DEBUG/AndroidRuntime(225): Shutting down VM
11-04 11:45:12.834: WARN/dalvikvm(225): threadid=3: thread exiting with uncaught exception (group=0x4001b188)
11-04 11:45:12.834: ERROR/AndroidRuntime(225): Uncaught handler: thread main exiting due to uncaught exception
11-04 11:45:12.894: ERROR/AndroidRuntime(225): java.lang.RuntimeException: Unable to start activity ComponentInfo{com.weuni.android.mups/com.weuni.android.mups.ViewCampusActivity}: java.lang.NullPointerException
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2496)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:2512)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at android.app.ActivityThread.access$2200(ActivityThread.java:119)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1863)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at android.os.Handler.dispatchMessage(Handler.java:99)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at android.os.Looper.loop(Looper.java:123)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at android.app.ActivityThread.main(ActivityThread.java:4363)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at java.lang.reflect.Method.invokeNative(Native Method)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at java.lang.reflect.Method.invoke(Method.java:521)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:860)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:618)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at dalvik.system.NativeStart.main(Native Method)
11-04 11:45:12.894: ERROR/AndroidRuntime(225): Caused by: java.lang.NullPointerException
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at com.weuni.android.mups.ViewCampusActivity.setupWebView(ViewCampusActivity.java:41)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at com.weuni.android.mups.ViewCampusActivity.onCreate(ViewCampusActivity.java:35)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1047)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:2459)
11-04 11:45:12.894: ERROR/AndroidRuntime(225):     ... 11 more
11-04 11:45:12.934: INFO/Process(52): Sending signal. PID: 225 SIG: 3
11-04 11:45:12.944: INFO/dalvikvm(225): threadid=7: reacting to signal 3
11-04 11:45:12.944: ERROR/dalvikvm(225): Unable to open stack trace file '/data/anr/traces.txt': Permission denied
11-04 11:45:13.165: DEBUG/ddm-heap(144): Got feature list request
11-04 11:45:13.265: DEBUG/ddm-heap(158): Got feature list request
11-04 11:45:13.315: INFO/ARMAssembler(52): generated scanline__00000077:03515104_00000000_00000000 [ 33 ipp] (47 ins) at [0x4bdcb0:0x4bdd6c] in 591000 ns
11-04 11:45:13.345: INFO/ARMAssembler(52): generated scanline__00000177:03515104_00001001_00000000 [ 91 ipp] (114 ins) at [0x4bdd70:0x4bdf38] in 752000 ns
11-04 11:45:13.375: DEBUG/ddm-heap(182): Got feature list request
11-04 11:45:13.385: DEBUG/ddm-heap(198): Got feature list request
11-04 11:45:14.265: DEBUG/NetworkLocationProvider(52): updateNetworkState(): Updating network state to 2
11-04 11:45:14.294: DEBUG/NetworkLocationProvider(52): onCellLocationChanged [0,0]
11-04 11:45:14.305: DEBUG/NetworkLocationProvider(52): onDataConnectionStateChanged 3
11-04 11:45:14.844: INFO/ActivityManager(52): Start proc com.svox.pico for broadcast com.svox.pico/.VoiceDataInstallerReceiver: pid=242 uid=10019 gids={}
11-04 11:45:14.995: DEBUG/ddm-heap(242): Got feature list request
11-04 11:45:15.624: DEBUG/MediaScanner(158): opendir /system/media/ failed, errno: 2
11-04 11:45:15.634: DEBUG/MediaScanner(158):  prescan time: 5425ms
11-04 11:45:15.634: DEBUG/MediaScanner(158):     scan time: 18ms
11-04 11:45:15.644: DEBUG/MediaScanner(158): postscan time: 2ms
11-04 11:45:15.644: DEBUG/MediaScanner(158):    total time: 5445ms
11-04 11:45:15.664: DEBUG/MediaScannerService(158): done scanning volume internal
11-04 11:45:15.674: DEBUG/MediaScannerService(158): start scanning volume external
11-04 11:45:15.694: VERBOSE/MediaProvider(158): /sdcard volume ID: 283779103
11-04 11:45:15.835: VERBOSE/MediaProvider(158): Attached volume: external
11-04 11:45:15.995: VERBOSE/MediaScanner(158): pruneDeadThumbnailFiles... android.database.sqlite.SQLiteCursor@43bb5fd0
11-04 11:45:16.005: VERBOSE/MediaScanner(158): /pruneDeadThumbnailFiles... android.database.sqlite.SQLiteCursor@43bb5fd0
11-04 11:45:16.036: DEBUG/MediaScanner(158):  prescan time: 123ms
11-04 11:45:16.036: DEBUG/MediaScanner(158):     scan time: 4ms
11-04 11:45:16.036: DEBUG/MediaScanner(158): postscan time: 52ms
11-04 11:45:16.036: DEBUG/MediaScanner(158):    total time: 179ms
11-04 11:45:16.065: DEBUG/MediaScannerService(158): done scanning volume external
11-04 11:45:19.655: INFO/Process(225): Sending signal. PID: 225 SIG: 9
11-04 11:45:19.685: INFO/ActivityManager(52): Process com.weuni.android.mups (pid 225) has died.
11-04 11:45:19.685: WARN/GpsLocationProvider(52): Unneeded remove listener for uid 1000
11-04 11:45:19.685: DEBUG/GpsLocationProvider(52): stopNavigating
11-04 11:45:19.795: INFO/UsageStats(52): Unexpected resume of com.android.launcher while already resumed in com.weuni.android.mups
11-04 11:45:20.085: WARN/InputManagerService(52): Window already focused, ignoring focus gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@43d2d030
11-04 11:45:24.585: WARN/ResourceType(52): Resources don't contain package for resource number 0x7f0700e5
11-04 11:45:24.595: WARN/ResourceType(52): Resources don't contain package for resource number 0x7f020031
11-04 11:45:24.595: WARN/ResourceType(52): Resources don't contain package for resource number 0x7f020030
11-04 11:45:24.595: WARN/ResourceType(52): Resources don't contain package for resource number 0x7f050000
11-04 11:45:24.605: WARN/ResourceType(52): Resources don't contain package for resource number 0x7f060001
11-04 11:45:24.625: WARN/ResourceType(52): Resources don't contain package for resource number 0x7f060000

Answer 1

11-04 11:45:12.894: ERROR/AndroidRuntime(225): Caused by: java.lang.NullPointerException 11-04 11:45:12.894: ERROR/AndroidRuntime(225): at com.weuni.android.mups.ViewCampusActivity.setupWebView(ViewCampusActivity.java:41)

It looks like you're trying to access a null object in the setupWebView() methood of your activity, specifically line 41. Since we don't have all the code and I cant count the lines accurately, I'm willing to bet your mostRecentLocation object is null when trying to call mostRecentLocation.getLatitude() and mostRecentLocation.getLongitude. Check that it's not null before trying to call those methods. The GPS receiver can sometimes be slow and may take a while to actually get a location.

---

Comment reply:

The problem is you're calling setupWebView() before a location is actually received. If mostRecentLocation is null, there is nothing you can really do about it until a location is received.

You might have to re-think how your app works just slightly. If mostRecentLocation is null, maybe display an error or a dialog that says you're waiting for a location. Then when a location is actually received, onLocationChanged will be called and you set the new location in the WebView there.