check if fragment is attached in fragment asynctasks

src/org/fox/ttrss/ArticlePager.java

@@ -144,6 +144,8 @@ public class ArticlePager extends Fragment {
 
 			@Override
 			protected void onPostExecute(JsonElement result) {
+				if (isDetached()) return;
+				
 				m_activity.setProgressBarVisibility(false);
 
 				super.onPostExecute(result);

src/org/fox/ttrss/FeedCategoriesFragment.java

@@ -255,6 +255,8 @@ public class FeedCategoriesFragment extends Fragment implements OnItemClickListe
 		
 		@Override
 		protected void onPostExecute(JsonElement result) {
+			if (isDetached()) return;
+			
 			m_activity.setProgressBarVisibility(false);
 
 			if (result != null) {

src/org/fox/ttrss/FeedsFragment.java

@@ -343,6 +343,8 @@ public class FeedsFragment extends Fragment implements OnItemClickListener, OnSh
 		
 		ApiRequest req = new ApiRequest(getActivity().getApplicationContext()) {
 			protected void onPostExecute(JsonElement result) {
+				if (isDetached()) return;
+				
 				if (result != null) {
 
 					try {
@@ -399,6 +401,8 @@ public class FeedsFragment extends Fragment implements OnItemClickListener, OnSh
 
 		@Override
 		protected void onPostExecute(JsonElement result) {
+			if (isDetached()) return;
+			
 			m_activity.setProgressBarVisibility(false);
 
 			if (result != null) {
@@ -632,6 +636,8 @@ public class FeedsFragment extends Fragment implements OnItemClickListener, OnSh
 		}
 		
 		protected void onPostExecute(Integer result) {
+			if (isDetached()) return;
+			
 			m_adapter.notifyDataSetInvalidated();
 		}
 		

src/org/fox/ttrss/HeadlinesFragment.java

@@ -368,6 +368,8 @@ public class HeadlinesFragment extends Fragment implements OnItemClickListener,
 
 				@Override
 				protected void onPostExecute(JsonElement result) {
+					if (isDetached()) return;
+					
 					m_activity.setProgressBarVisibility(false);
 					
 					super.onPostExecute(result);	

src/org/fox/ttrss/OnlineActivity.java

@@ -545,7 +545,9 @@ public class OnlineActivity extends CommonActivity {
 
 				ApiRequest req = new ApiRequest(getApplicationContext()) {
 					protected void onPostExecute(JsonElement result) {
-						hf.refresh(false);
+						if (hf.isAdded()) {
+							hf.refresh(false);
+						}
 					}
 				};