AsyncTask: cancel background tasks when the fragments are destroyed.

I assumed the lifecycle of the fragment and the task were tied because they
are tied to the instance, but it looks like I was wrong. We need to
explicitly cancel tasks.

app/src/main/java/com/etesync/syncadapter/ui/CollectionMembersListFragment.java

@@ -40,6 +40,7 @@ public class CollectionMembersListFragment extends ListFragment implements Adapt
     private Account account;
     private CollectionInfo info;
     private JournalEntity journalEntity;
+    private AsyncTask asyncTask;
 
     private TextView emptyTextView;
 
@@ -73,7 +74,7 @@ public class CollectionMembersListFragment extends ListFragment implements Adapt
 
     @Override
     public void refresh() {
-        new JournalMembersFetch().execute();
+        asyncTask = new JournalMembersFetch().execute();
     }
 
     @Override
@@ -85,6 +86,13 @@ public class CollectionMembersListFragment extends ListFragment implements Adapt
         getListView().setOnItemClickListener(this);
     }
 
+    @Override
+    public void onDestroyView() {
+        super.onDestroyView();
+        if (asyncTask != null)
+            asyncTask.cancel(true);
+    }
+
     @Override
     public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
         final JournalManager.Member member = (JournalManager.Member) getListAdapter().getItem(position);

app/src/main/java/com/etesync/syncadapter/ui/JournalItemActivity.java

@@ -166,6 +166,7 @@ public class JournalItemActivity extends BaseActivity implements Refreshable {
     public static class PrettyFragment extends Fragment {
         CollectionInfo info;
         SyncEntry syncEntry;
+        private AsyncTask asyncTask;
 
         public static PrettyFragment newInstance(CollectionInfo info, SyncEntry syncEntry) {
             PrettyFragment frag = new PrettyFragment();
@@ -186,17 +187,24 @@ public class JournalItemActivity extends BaseActivity implements Refreshable {
             switch (info.type) {
                 case ADDRESS_BOOK:
                     v = inflater.inflate(R.layout.contact_info, container, false);
-                    new LoadContactTask(v).execute();
+                    asyncTask = new LoadContactTask(v).execute();
                     break;
                 case CALENDAR:
                     v = inflater.inflate(R.layout.event_info, container, false);
-                    new LoadEventTask(v).execute();
+                    asyncTask = new LoadEventTask(v).execute();
                     break;
             }
 
             return v;
         }
 
+        @Override
+        public void onDestroyView() {
+            super.onDestroyView();
+            if (asyncTask != null)
+                asyncTask.cancel(true);
+        }
+
         private class LoadEventTask extends AsyncTask<Void, Void, Event> {
             View view;
             LoadEventTask(View v) {

app/src/main/java/com/etesync/syncadapter/ui/journalviewer/ListEntriesFragment.java

@@ -41,6 +41,7 @@ public class ListEntriesFragment extends ListFragment implements AdapterView.OnI
     private EntityDataStore<Persistable> data;
     private CollectionInfo info;
     private JournalEntity journalEntity;
+    private AsyncTask asyncTask;
 
     private TextView emptyTextView;
 
@@ -74,11 +75,18 @@ public class ListEntriesFragment extends ListFragment implements AdapterView.OnI
     public void onViewCreated(View view, Bundle savedInstanceState) {
         super.onViewCreated(view, savedInstanceState);
 
-        new JournalFetch().execute();
+        asyncTask = new JournalFetch().execute();
 
         getListView().setOnItemClickListener(this);
     }
 
+    @Override
+    public void onDestroyView() {
+        super.onDestroyView();
+        if (asyncTask != null)
+            asyncTask.cancel(true);
+    }
+
     @Override
     public void onItemClick(AdapterView<?> parent, View view, int position, long id) {
         EntryEntity entry = (EntryEntity) getListAdapter().getItem(position);