Added state when an invalid query (generating a 404 code) is detected by the SyncAdapter.

app/src/main/java/com/example/android/sunshine/app/ForecastFragment.java

@@ -305,6 +305,9 @@ public class ForecastFragment extends Fragment implements LoaderManager.LoaderCa
                     case SunshineSyncAdapter.LOCATION_STATUS_SERVER_INVALID:
                         message = R.string.empty_forecast_list_server_error;
                         break;
+                    case SunshineSyncAdapter.LOCATION_STATUS_INVALID:
+                        message = R.string.empty_forecast_list_invalid_location;
+                        break;
                     default:
                         if (!Utility.isNetworkAvailable(getActivity()) ) {
                             message = R.string.empty_forecast_list_no_network;

app/src/main/java/com/example/android/sunshine/app/SettingsActivity.java

@@ -113,6 +113,9 @@ public class SettingsActivity extends PreferenceActivity
     @Override
     public void onSharedPreferenceChanged(SharedPreferences sharedPreferences, String key) {
         if ( key.equals(getString(R.string.pref_location_key)) ) {
+            // we've changed the location
+            // first clear locationStatus
+            Utility.resetLocationStatus(this);
             SunshineSyncAdapter.syncImmediately(this);
         } else if ( key.equals(getString(R.string.pref_units_key)) ) {
             // units have changed. update lists of weather entries accordingly

app/src/main/java/com/example/android/sunshine/app/Utility.java

@@ -277,4 +277,15 @@ public class Utility {
         SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(c);
         return sp.getInt(c.getString(R.string.pref_location_status_key), SunshineSyncAdapter.LOCATION_STATUS_UNKNOWN);
     }
+
+    /**
+     * Resets the location status.  (Sets it to SunshineSyncAdapter.LOCATION_STATUS_UNKNOWN)
+     * @param c Context used to get the SharedPreferences
+     */
+    static public void resetLocationStatus(Context c){
+        SharedPreferences sp = PreferenceManager.getDefaultSharedPreferences(c);
+        SharedPreferences.Editor spe = sp.edit();
+        spe.putInt(c.getString(R.string.pref_location_status_key), SunshineSyncAdapter.LOCATION_STATUS_UNKNOWN);
+        spe.apply();
+    }
 }

app/src/main/java/com/example/android/sunshine/app/sync/SunshineSyncAdapter.java

@@ -71,15 +71,14 @@ public class SunshineSyncAdapter extends AbstractThreadedSyncAdapter {
     private static final int INDEX_SHORT_DESC = 3;
 
     @Retention(RetentionPolicy.SOURCE)
-    @IntDef({LOCATION_STATUS_OK, LOCATION_STATUS_SERVER_DOWN, LOCATION_STATUS_SERVER_INVALID,  LOCATION_STATUS_UNKNOWN})
+    @IntDef({LOCATION_STATUS_OK, LOCATION_STATUS_SERVER_DOWN, LOCATION_STATUS_SERVER_INVALID,  LOCATION_STATUS_UNKNOWN, LOCATION_STATUS_INVALID})
     public @interface LocationStatus {}
 
     public static final int LOCATION_STATUS_OK = 0;
     public static final int LOCATION_STATUS_SERVER_DOWN = 1;
-    public static final int
+    public static final int LOCATION_STATUS_SERVER_INVALID = 2;
-            LOCATION_STATUS_SERVER_INVALID = 2;
+    public static final int LOCATION_STATUS_UNKNOWN = 3;
-    public static final int
+    public static final int LOCATION_STATUS_INVALID = 4;
-            LOCATION_STATUS_UNKNOWN = 3;
 
     public SunshineSyncAdapter(Context context, boolean autoInitialize) {
         super(context, autoInitialize);
@@ -218,8 +217,27 @@ public class SunshineSyncAdapter extends AbstractThreadedSyncAdapter {
         final String OWM_DESCRIPTION = "main";
         final String OWM_WEATHER_ID = "id";
 
+        final String OWM_MESSAGE_CODE = "cod";
+
         try {
             JSONObject forecastJson = new JSONObject(forecastJsonStr);
+
+            // do we have an error?
+            if ( forecastJson.has(OWM_MESSAGE_CODE) ) {
+                int errorCode = forecastJson.getInt(OWM_MESSAGE_CODE);
+
+                switch (errorCode) {
+                    case HttpURLConnection.HTTP_OK:
+                        break;
+                    case HttpURLConnection.HTTP_NOT_FOUND:
+                        setLocationStatus(getContext(), LOCATION_STATUS_INVALID);
+                        return;
+                    default:
+                        setLocationStatus(getContext(), LOCATION_STATUS_SERVER_DOWN);
+                        return;
+                }
+            }
+
             JSONArray weatherArray = forecastJson.getJSONArray(OWM_LIST);
 
             JSONObject cityJson = forecastJson.getJSONObject(OWM_CITY);

app/src/main/res/values/strings.xml

@@ -117,5 +117,6 @@
     <string name="empty_forecast_list_no_network">No weather information available. The network is not available to fetch weather data.</string>
     <string name="empty_forecast_list_server_down">No weather information available. The server is not returning data.</string>
     <string name="empty_forecast_list_server_error">No weather information available. The server is not returning valid data. Please check for an updated version of Sunshine.</string>
+    <string name="empty_forecast_list_invalid_location">No weather information available. The location in settings is not recognized by the weather server.</string>
 
 </resources>