我正在使用RecyclerView，它必须是Draggable＆amp;滑动式。一切都很完美。
数据正在一个名为ExerciseDataProvider＆amp;的班级中被提取。 RV代码是另一个片段RecyclerListViewFragment。
问题是我无法通过postExecute方法通知FetchExercise更改的数据。因此，数据不会在RV中填充。
请指导我正确的方向。
活性
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);
}
}
答案 0 :(得分：3)
要从数据提供者类中的recyclerView更新onPostExecute，您的onPostExecute应该可以访问已定义context的{{1}}。
由于您在recyclerView类中定义了FetchExercise异步任务，请尝试将ExerciseDataProvider activity传递给context的构造函数，然后将其传递给{ {1}}异步任务，如下所述：getting context in AsyncTask
ExerciseDataProvider使用FetchExercise更新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
}
}
}
。
<强>更新
第1步
定义context，该recyclerView将通知您interface内的数据集更改，该类会初始化您的activity并将data provider class传递给activity context的构造函数。
data provider class第2步
将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;
}
}
参数添加到context的构造函数，并使用它来通知实现接口的活动以通知数据集更改。
ExerciseDataProvider第3步
在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();
}
}
}
中实施上面定义的interface，并在其中通知activity class recyclerview
adapter答案 1 :(得分：0)
我认为@random是正确的，你应该在post post上通知你的Recycle视图。
@Override
protected void onPostExecute(Void aVoid) {
mRecyclerViewAdapter.notifyDataSetChanged();
super.onPostExecute(aVoid);
}
或者如果你在异步任务中做了一些事情来添加/删除数据集中的某些内容，你会这样做：
@Override
protected void onPostExecute(Void aVoid) {
mRecyclerViewAdapter.notifyItemRemoved(itemposition); // or item added
mRecyclerViewAdapter.notifyDataSetChanged();
super.onPostExecute(aVoid);
}
希望它有所帮助！