Android – cannot update recyclerview from my model class?
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Android
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The problem is that I cannot notify fetchexecute of the changed data through the postexecute method. Therefore, the data will not be populated in the RV
Please guide me in the right direction
activity
public class DraggableSwipeableExampleActivity extends AppCompatActivity {
private static final String FRAGMENT_TAG_DATA_PROVIDER = "data provider";
private static final String FRAGMENT_LIST_VIEW = "list view";
private static final String FRAGMENT_TAG_ITEM_PINNED_DIALOG = "item pinned dialog";
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_demo);
if (savedInstanceState == null) {
getSupportFragmentManager().beginTransaction()
.add(new ExampleDataProviderFragment(), FRAGMENT_TAG_DATA_PROVIDER)
.commit();
getSupportFragmentManager().beginTransaction()
.add(R.id.container, new RecyclerListViewFragment(), FRAGMENT_LIST_VIEW)
.commit();
}
}
public AbstractDataProvider getDataProvider() {
final Fragment fragment = getSupportFragmentManager().findFragmentByTag(FRAGMENT_TAG_DATA_PROVIDER);
return ((ExampleDataProviderFragment) fragment).getDataProvider();
}
data provider
public class ExerciseDataProvider extends AbstractDataProvider {
private List<ConcreteData> mData;
private ConcreteData mLastRemovedData;
private int mLastRemovedPosition = -1;
public ExerciseDataProvider() {
new FetchExercise().execute();
mData = new LinkedList<>();
}
class FetchExercise extends AsyncTask<Void,Void,Void> {
@Override
protected Void doInBackground(Void... params) {
final int viewType = 0;
final int swipeReaction = RecyclerViewSwipeManager.REACTION_CAN_SWIPE_UP | RecyclerViewSwipeManager.REACTION_CAN_SWIPE_DOWN;
String url = "https://gist.githubusercontent.com/fake/cb9aa5494e7ee36ac3ca/raw/a4abfd19368063/exercise.JSON";
Log.d("Path", url);
try {
OkHttpClient client = new OkHttpClient();
Request request = new Request.Builder().url(url).build();
Response response = client.newCall(request).execute();
String jsonData = response.body().string();
try {
JSONArray jsonArray = new JSONArray(jsonData);
for (int i = 0; i < jsonArray.length(); i++) {
final long id = i;
JSONObject jsonObject = jsonArray.getJSONObject(i);
String exercise_name = jsonObject.getString("name");
int exercise_duration = jsonObject.getInt("duration");
mData.add(new ConcreteData(id, viewType, exercise_name, exercise_duration, swipeReaction));
Log.d("exercise_name", exercise_name);
}
} catch (JSONException e) {
e.printStackTrace();
}
} catch (IOException e) {
e.printStackTrace();
}
return null;
}
@Override
protected void onPostExecute(Void aVoid) {
super.onPostExecute(aVoid);
}
}
@Override
public int getCount() {
return mData.size();
}
@Override
public Data getItem(int index) {
if (index < 0 || index >= getCount()) {
throw new indexoutofboundsexception("index = " + index);
}
return mData.get(index);
}
@Override
public int undoLastRemoval() {
if (mLastRemovedData != null) {
int insertedPosition;
if (mLastRemovedPosition >= 0 && mLastRemovedPosition < mData.size()) {
insertedPosition = mLastRemovedPosition;
} else {
insertedPosition = mData.size();
}
mData.add(insertedPosition, mLastRemovedData);
mLastRemovedData = null;
mLastRemovedPosition = -1;
return insertedPosition;
} else {
return -1;
}
}
@Override
public void moveItem(int fromPosition, int toPosition) {
if (fromPosition == toPosition) {
return;
}
final ConcreteData item = mData.remove(fromPosition);
mData.add(toPosition, item);
mLastRemovedPosition = -1;
}
@Override
public void removeItem(int position) {
//noinspection UnnecessaryLocalVariable
final ConcreteData removedItem = mData.remove(position);
mLastRemovedData = removedItem;
mLastRemovedPosition = position;
}
public static final class ConcreteData extends Data {
private final long mId;
private final String mText;
private final int mViewType;
private final int mDuration;
private boolean mPinned;
ConcreteData(long id, int viewType, String text, int duration, int swipeReaction) {
mId = id;
mViewType = viewType;
mText = text;
mDuration = duration;
}
@Override
public int getViewType() {
return mViewType;
}
@Override
public int getDuration() {
return mDuration;
}
@Override
public long getId() {
return mId;
}
@Override
public String toString() {
return mText;
}
@Override
public String getText() {
return mText;
}
@Override
public boolean isPinned() {
return mPinned;
}
@Override
public void setPinned(boolean pinned) {
mPinned = pinned;
}
}
}
RecyclerListViewFragment
public class RecyclerListViewFragment extends Fragment {
private RecyclerView mRecyclerView;
private RecyclerView.LayoutManager mLayoutManager;
private RecyclerView.Adapter mAdapter;
private RecyclerView.Adapter mWrappedAdapter;
private RecyclerViewDragDropManager mRecyclerViewDragDropManager;
private RecyclerViewSwipeManager mRecyclerViewSwipeManager;
private RecyclerViewTouchActionGuardManager mRecyclerViewTouchActionGuardManager;
public RecyclerListViewFragment() {
super();
}
@Override
public View onCreateView(LayoutInflater inflater, @Nullable ViewGroup container, @Nullable Bundle savedInstanceState) {
return inflater.inflate(R.layout.fragment_recycler_list_view, container, false);
}
@Override
public void onViewCreated(View view, @Nullable Bundle savedInstanceState) {
super.onViewCreated(view, savedInstanceState);
//noinspection ConstantConditions
mRecyclerView = (RecyclerView) getView().findViewById(R.id.recycler_view);
mLayoutManager = new linearlayoutmanager(getContext());
// touch guard manager (this class is required to suppress scrolling while swipe-dismiss animation is running)
mRecyclerViewTouchActionGuardManager = new RecyclerViewTouchActionGuardManager();
mRecyclerViewTouchActionGuardManager.setInterceptVerticalScrollingWhileAnimationRunning(true);
mRecyclerViewTouchActionGuardManager.setEnabled(true);
// drag & drop manager
mRecyclerViewDragDropManager = new RecyclerViewDragDropManager();
mRecyclerViewDragDropManager.setDraggingItemShadowDrawable(
(NinePatchDrawable) ContextCompat.getDrawable(getContext(), R.drawable.material_shadow_z3));
// swipe manager
mRecyclerViewSwipeManager = new RecyclerViewSwipeManager();
//adapter
final MyDraggableSwipeableItemAdapter myItemAdapter = new MyDraggableSwipeableItemAdapter(getDataProvider());
myItemAdapter.setEventListener(new MyDraggableSwipeableItemAdapter.EventListener() {
@Override
public void onItemRemoved(int position) {
((DraggableSwipeableExampleActivity) getActivity()).onItemRemoved(position);
}
@Override
public void onItemViewClicked(View v, boolean pinned) {
onItemViewClick(v, pinned);
}
});
mAdapter = myItemAdapter;
mWrappedAdapter = mRecyclerViewDragDropManager.createWrappedAdapter(myItemAdapter); // wrap for dragging
mWrappedAdapter = mRecyclerViewSwipeManager.createWrappedAdapter(mWrappedAdapter); // wrap for swiping
final GeneralItemAnimator animator = new SwipeDismissItemAnimator();
animator.setSupportsChangeAnimations(false);
mRecyclerView.setLayoutManager(mLayoutManager);
mRecyclerView.setAdapter(mWrappedAdapter); // requires *wrapped* adapter
mRecyclerView.setItemAnimator(animator);
// additional decorations
//noinspection StatementWithEmptyBody
if (supportsViewElevation()) {
// Lollipop or later has native drop shadow feature. ItemShadowDecorator is not required.
} else {
mRecyclerView.addItemDecoration(new ItemShadowDecorator((NinePatchDrawable) ContextCompat.getDrawable(getContext(), R.drawable.material_shadow_z1)));
}
mRecyclerView.addItemDecoration(new SimpleListDividerDecorator(ContextCompat.getDrawable(getContext(), R.drawable.list_divider_h), true));
mRecyclerViewTouchActionGuardManager.attachRecyclerView(mRecyclerView);
mRecyclerViewSwipeManager.attachRecyclerView(mRecyclerView);
mRecyclerViewDragDropManager.attachRecyclerView(mRecyclerView);
}
@Override
public void onPause() {
mRecyclerViewDragDropManager.cancelDrag();
super.onPause();
}
@Override
public void onDestroyView() {
if (mRecyclerViewDragDropManager != null) {
mRecyclerViewDragDropManager.release();
mRecyclerViewDragDropManager = null;
}
if (mRecyclerViewSwipeManager != null) {
mRecyclerViewSwipeManager.release();
mRecyclerViewSwipeManager = null;
}
if (mRecyclerViewTouchActionGuardManager != null) {
mRecyclerViewTouchActionGuardManager.release();
mRecyclerViewTouchActionGuardManager = null;
}
if (mRecyclerView != null) {
mRecyclerView.setItemAnimator(null);
mRecyclerView.setAdapter(null);
mRecyclerView = null;
}
if (mWrappedAdapter != null) {
WrapperAdapterUtils.releaseAll(mWrappedAdapter);
mWrappedAdapter = null;
}
mAdapter = null;
mLayoutManager = null;
super.onDestroyView();
}
private void onItemViewClick(View v, boolean pinned) {
int position = mRecyclerView.getChildAdapterPosition(v);
if (position != RecyclerView.NO_POSITION) {
((DraggableSwipeableExampleActivity) getActivity()).onItemClicked(position);
}
}
public AbstractDataProvider getDataProvider() {
return ((DraggableSwipeableExampleActivity) getActivity()).getDataProvider();
}
public void notifyItemChanged(int position) {
mAdapter.notifyItemChanged(position);
}
public void notifyItemInserted(int position) {
mAdapter.notifyItemInserted(position);
mRecyclerView.scrollToPosition(position);
}
}
resolvent:
To update the recyclerview from onpostexecute in the data provider class, your onpostexecute should have access to the context in which the recyclerview is defined
Since your fetchexercise asynchronous task is defined in the exercisedataprovider class, try passing the activity context to the constructor of exercisedataprovider, and then passing it to the fetchexercise asynchronous task, as follows: getting context in asynctask
public class MyCustomTask extends AsyncTask<Void, Void, Long> {
private Context mContext;
public MyCustomTask (Context context){
mContext = context;
}
protected void onPostExecute(Long result) {
//use mContext to update recycler view
}
}
}
Update recyclerview. With context
UPDATE
Step 1
Define an interface that will notify your dataset change activity in the class. The class initializes the data provider class and passes the activity context to the constructor of the data provider class
public class ExampleDataProviderFragment extends Fragment {
private AbstractDataProvider mDataProvider;
//Define an interface that will notify your activity of data set change
public interface EventListener {
void onNotifyDataSetChanged();
}
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setRetainInstance(true);
//Pass activity context to ExerciseDataProvider
mDataProvider = new ExerciseDataProvider(getActivity());
}
public AbstractDataProvider getDataProvider() {
return mDataProvider;
}
}
Step 2
Add the context parameter to the constructor of exercisedataprovider and use it to notify the activity of the implementation interface to notify the dataset of changes
public class ExerciseDataProvider extends AbstractDataProvider {
private List<ConcreteData> mData;
private ConcreteData mLastRemovedData;
private int mLastRemovedPosition = -1;
//Add context parameter to constructor
public ExerciseDataProvider(Context context) {
//Pass context to async task
new FetchExercise(context).execute();
mData = new LinkedList<>();
}
class FetchExercise extends AsyncTask<Void,Void,Integer> {
Context mContext;
public FetchExercise(Context context) {
mContext = context;
}
@Override
protected Integer doInBackground(Void... params) {
...
return 1;
}
@Override
protected void onPostExecute(Integer result) {
super.onPostExecute(result);
//Typecast context to interface defined above
//and notify dataset changes by calling its method
ExampleDataProviderFragment.EventListener eventListener = (ExampleDataProviderFragment.EventListener)mContext;
eventListener.onNotifyDataSetChanged();
}
}
}
Step 3
Implement the interface defined above in your activity class and notify the recyclerview adapter in it
public class DraggableSwipeableExampleActivity extends AppCompatActivity
implements ExampleDataProviderFragment.EventListener {
@Override
protected void onCreate(Bundle savedInstanceState) {
...
}
//implement interface method and notify recyclerview of changes
@Override
public void onNotifyDataSetChanged() {
Fragment fragment = getSupportFragmentManager().findFragmentByTag(FRAGMENT_LIST_VIEW);
// you might need to change visibility of `mWrappedAdapter` in the fragment that defines it or create a getter for it so that you can access it here
((RecyclerListViewFragment) fragment).mWrappedAdapter.notifyDataSetChanged();
}
...
}
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