问题
I am fetching some data from API and presenting each item as a RecyclerViewPager slide. So, I have made an async task inside onScrollListener to check scroll actions and when the user slides 5 items asynctask fetches the Items of page 2 and in the doInBackGround function the data will be added to the array and array will be added to the recycler view pager.
Everything works fine but I need to stop scrolling at 5 slide for a few seconds(Minimum 5 sec) or else the recyclerView won't show the 2nd page slides.
How to solve this problem. This is the code I am using for the onScrollListener and asyncTask functions.
Code :
private void initRecycler(){
final RecyclerViewPager mRecyclerView = (RecyclerViewPager) findViewById(R.id.list);
// setLayoutManager like normal RecyclerView, you do not need to change any thing.
final LinearLayoutManager layout = new LinearLayoutManager(this,LinearLayoutManager.HORIZONTAL,false);
mRecyclerView.setLayoutManager(layout);
//set adapter
//You just need to implement ViewPageAdapter by yourself like a normal RecyclerView.Adpater.
RecyclerViewAdapter adapter = new RecyclerViewAdapter(ImageUrls, ImageNames, ImageDesc, this);
mRecyclerView.setAdapter(adapter);
mRecyclerView.addOnScrollListener(new RecyclerView.OnScrollListener() {
@Override
public void onScrolled(RecyclerView recyclerView, int dx, int dy) {
super.onScrolled(recyclerView, dx, dy);
visibleItemCount = layout.getChildCount();
totalItemCount = layout.getItemCount();
firstVisibleItem = layout.findFirstVisibleItemPosition();
// int aaa = totalItemCount - visibleItemCount;
// int bbb = firstVisibleItem + visibleThreshold;
// Log.d("tag" ,"totalItemCount : " + totalItemCount + "| visibleItemCount : " + visibleItemCount);
Log.d("tag" ,"totalItemCount : " + totalItemCount + "| previousTotal : " + previousTotal);
Log.d("tag", "firstVisibleItem :" + firstVisibleItem + " | totalItemCount :" + totalItemCount);
if (loading) {
if (totalItemCount > previousTotal) {
loading = false;
previousTotal = totalItemCount;
}
}
if (!loading && (firstVisibleItem + 5)
== (totalItemCount)) {
Log.i("Ya!", "end called");
page += 1;
String url = "http://url.in/wp-json/wp/v2/posts?page="+page+"&_embed";
Log.d( url ,": ");
// Do something
final OkHttpClient client2 = new OkHttpClient();
final Request request2 = new Request.Builder()
.url(url)
.build();
@SuppressLint("StaticFieldLeak") AsyncTask<Void, Void, String> asyncTask = new AsyncTask<Void, Void, String>() {
private static final String TAG = "SlideFragment";
@Override
protected String doInBackground(Void... params) {
try {
Response response2 = client2.newCall(request2).execute();
if (!response2.isSuccessful()) {
Log.d(TAG, "doInBackground: REsponse Un Successfull - 56");
response2.body().close();
return null;
}
String Data2 = response2.body().string();
response2.body().close();
return Data2;
} catch (Exception e) {
e.printStackTrace();
Log.d(TAG, "doInBackground: Exceptione on line63");
return null;
}
}
@Override
protected void onPostExecute(String Data2) {
super.onPostExecute(Data2);
if (Data2 != null) {
Log.d(TAG, "onPostExecute: 188 LINE");
try {
JSONArray json = new JSONArray(Data2);
for (int i = 0; i < json.length(); i++) {
JSONObject post = json.getJSONObject(i);
String title = post.getJSONObject("title").getString("rendered");
String description = post.getJSONObject("excerpt").getString("rendered");
String imgURL = post.getJSONObject("_embedded").getJSONArray("wp:featuredmedia").getJSONObject(0).getJSONObject("media_details").getString("file");
String imagUrl = "http://url.in/wp-content/uploads/" + imgURL;
ImageNames.add(title);
ImageDesc.add(description);
ImageUrls.add(imagUrl);
Log.d(TAG, "onPostExecute: arrayList Created" );
}
}catch(JSONException j){
j.printStackTrace();
Log.d(TAG, "onPostExecute: on line 121");
}
}
}
};
asyncTask.execute();
loading = true;
}
}
});
}
}
回答1:
I guess you should cancel task manually before making another request, as one task can only be executed once according to rules given in the documentation
来源：https://stackoverflow.com/questions/52856322/doinbackground-in-async-task-not-working-properly