Fixes to basic navigation.

app/src/main/java/pl/tpolgrabia/urbanexplorer/MainActivity.java

@@ -43,7 +43,7 @@ public class MainActivity extends ActionBarActivity {
     private GestureDetector.OnGestureListener swipeHandler;
     private PanoramioImageInfo photoInfo;
     private ProgressDialog progressDlg;
-    private MainActivityState oldFragmentId = MainActivityState.PANORAMIO
+    private MainActivityState oldFrag = MainActivityState.PANORAMIO_SHOWER;
     private boolean savedConfiguration;
 
     private static final Map<Integer, String> fragTags = new HashMap<>();
@@ -78,7 +78,7 @@ public class MainActivity extends ActionBarActivity {
         lg.trace("onCreate");
         setContentView(R.layout.activity_main);
 
-        HelperUtils.initErrorAndDebugHanlers();
+        HelperUtils.initErrorAndDebugHanlers(this);
         NetUtils.setGlobalProxyAuth(this);
 
         currFrag = MainActivityState.PANORAMIO;
@@ -198,9 +198,12 @@ public class MainActivity extends ActionBarActivity {
 
     private void switchFragment() {
 
+        if (currFrag == oldFrag) {
+            return;
+        }
+
         if (!savedConfiguration) {
             photoInfo = null;
-            currFrag = MainActivityState.PANORAMIO;
         }
 
         switch (currFrag) {
@@ -228,9 +231,9 @@ public class MainActivity extends ActionBarActivity {
 
         FragmentManager fragmentManager = getSupportFragmentManager();
         FragmentTransaction ctx = fragmentManager.beginTransaction();
-        lg.trace("old newFragment id: {}, current newFragment id: {}", oldFragmentId, currFrag);
+        lg.trace("old newFragment id: {}, current newFragment id: {}", oldFrag, currFrag);
 
-        HelperUtils.appendEffectToTransition(ctx, oldFragmentId, currFrag);
+        HelperUtils.appendEffectToTransition(ctx, oldFrag, currFrag);
         HelperUtils.traceAllAvailableFragments(fragmentManager);
 
         lg.trace("Trying to search newFragment by tag {}", tag);
@@ -261,18 +264,22 @@ public class MainActivity extends ActionBarActivity {
 
     public void swipeLeft() {
         lg.debug("Swiped left");
-        changeCurrentFragId((int)Math.max(AppConstants.MIN_FRAGMENT_ID, currFrag -1));
+        changeCurrentFragId(currFrag.prev());
         switchFragment();
     }
 
     private void changeCurrentFragId(MainActivityState nextFragmentId) {
-        oldFragmentId = currFrag;
+        if (nextFragmentId == null) {
+            oldFrag = currFrag;
+            return;
+        }
+        oldFrag = currFrag;
         currFrag = nextFragmentId;
     }
 
     public void swipeRight() {
         lg.debug("Swiped right");
-        changeCurrentFragId((int)Math.min(AppConstants.MAX_FRAGMENT_ID, currFrag +1));
+        changeCurrentFragId(currFrag.next());
         switchFragment();
     }
 

app/src/main/java/pl/tpolgrabia/urbanexplorer/callbacks/WikiInfoRunBrowserCallback.java

@@ -2,6 +2,7 @@ package pl.tpolgrabia.urbanexplorer.callbacks;
 
 import android.content.Intent;
 import android.net.Uri;
+import android.support.v4.app.FragmentActivity;
 import android.widget.Toast;
 import com.androidquery.callback.AjaxCallback;
 import com.androidquery.callback.AjaxStatus;
@@ -44,7 +45,13 @@ public class WikiInfoRunBrowserCallback extends AjaxCallback<JSONObject> {
                 .getString("fullurl");
             Intent intent = new Intent(Intent.ACTION_VIEW,
                 Uri.parse(wikiUrl));
-            wikiLocationsFragment.startActivity(intent);
+            FragmentActivity activity = wikiLocationsFragment.getActivity();
+            if (activity == null) {
+                lg.debug("Fragment is not attached to activity");
+                return;
+            }
+
+            activity.startActivity(intent);
         } catch (JSONException e) {
             lg.error("JSON error", e);
         }

app/src/main/java/pl/tpolgrabia/urbanexplorer/dto/MainActivityState.java

@@ -1,5 +1,7 @@
 package pl.tpolgrabia.urbanexplorer.dto;
 
+import pl.tpolgrabia.urbanexplorer.MainActivity;
+
 /**
  * Created by tpolgrabia on 19.09.16.
  */
@@ -17,4 +19,42 @@ public enum MainActivityState {
     public Integer getOrder() {
         return order;
     }
+
+    public MainActivityState prev() {
+        int val = Integer.MIN_VALUE;
+        MainActivityState greatestSmaller = null;
+
+        for (MainActivityState state : values()) {
+            if (state.getOrder() >= order || state.getOrder() < 0) {
+                continue;
+            }
+
+            // we need the greatest smaller
+
+            if (state.getOrder() > val) {
+                val = state.getOrder();
+                greatestSmaller = state;
+            }
+        }
+        return greatestSmaller;
+    }
+
+    public MainActivityState next() {
+        int val = Integer.MAX_VALUE;
+        MainActivityState smallestGreater = null;
+
+        for (MainActivityState state : values()) {
+            if (state.getOrder() <= order || state.getOrder() < 0) {
+                continue;
+            }
+
+            // we need the smallest greater
+
+            if (state.getOrder() < val) {
+                val = state.getOrder();
+                smallestGreater = state;
+            }
+        }
+        return smallestGreater;
+    }
 }

app/src/main/java/pl/tpolgrabia/urbanexplorer/fragments/HomeFragment.java

@@ -295,7 +295,13 @@ public class HomeFragment extends Fragment implements Refreshable {
                             return;
                         }
 
-                        ListView locations = (ListView) getView().findViewById(R.id.locations);
+                        final View view = getView();
+                        if (view == null) {
+                            lg.debug("View still not initialized");
+                            return;
+                        }
+
+                        ListView locations = (ListView) view.findViewById(R.id.locations);
                         if (locations == null) {
                             lg.trace("Empty locations");
                             return;

app/src/main/java/pl/tpolgrabia/urbanexplorer/fragments/WikiLocationsFragment.java

@@ -49,7 +49,7 @@ public class WikiLocationsFragment extends Fragment implements Refreshable {
     private static final String WIKI_APP_OBJECTS = "WIKI_APP_OBJECTS";
     private LocationManager locationService;
     private TextView currentLocation;
-    private ArrayList<WikiAppObject> appObjects;
+    private ArrayList<WikiAppObject> appObjects = new ArrayList<>();
     private int lastFetchSize = -1;
 
     public WikiLocationsFragment() {

app/src/main/java/pl/tpolgrabia/urbanexplorer/utils/HelperUtils.java

@@ -74,6 +74,10 @@ public class HelperUtils {
     }
 
     public static void appendEffectToTransition(FragmentTransaction ctx, MainActivityState old, MainActivityState curr) {
+        if (old.getOrder() == -1 || curr.getOrder() == -1) {
+            return;
+        }
+
         if (old != curr) {
             if (curr.getOrder() < old.getOrder()) {
                 // slide left animation