Please help me with the error: From RecyclerView, when you click on an item, you go to the activity with the Download and Read buttons. When you click on "Download", AsyncTask is launched (it loads the url list). After downloading, the button becomes inactive (according to the condition of having a folder with downloaded files). When you click on "Read" is a transition to another activit, to view images. Conventionally - this is the first book, its files for viewing. So, when you try to download the second book, everything looks fine, but you cannot view the files - they are not loaded. In the debugger, I run the download cycle for two books - it works unstably, then one file will load out of seven, then completely everything is as it should. If I clean the application data, the book that I loaded first normally works.

import android.content.Intent; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.net.Uri; import android.os.AsyncTask; import android.os.Handler; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.ImageView; import com.google.gson.Gson; import com.google.gson.reflect.TypeToken; import com.tonyodev.fetch.Fetch; import com.tonyodev.fetch.request.Request; import org.json.JSONArray; import org.json.JSONException; import org.json.JSONObject; import org.json.JSONTokener; import java.io.BufferedReader; import java.io.File; import java.io.InputStream; import java.io.InputStreamReader; import java.lang.reflect.Type; import java.net.HttpURLConnection; import java.net.URL; import java.util.ArrayList; import java.util.List; import java.util.concurrent.ExecutionException; import ru.yandex.matu1.toddlersbook.models.Book; import ru.yandex.matu1.toddlersbook.models.BookFiles; public class BookCardActivity extends AppCompatActivity { static final String TAG = "myLogs"; private int bookId; private String fileNamePath = "filesPath.json"; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_book_card); BookUriFromId(); String covers = MyJSON.getData(this, fileNamePath); ArrayList<String> coversPaths = getFilesPathFromFile(covers); ImageView imageView = (ImageView) findViewById(R.id.imageView); int posit = bookId-1; File imgFile = new File(coversPaths.get(posit)); Bitmap myBitmap = BitmapFactory.decodeFile(imgFile.getAbsolutePath()); imageView.setImageBitmap(myBitmap); Button buttonDownload = (Button) findViewById(R.id.button); Button buttonRead = (Button) findViewById(R.id.button2); String fileBookSt = "book_" + bookId + ".json"; File fileOfBook = new File(getApplicationContext().getFilesDir().getPath() + File.separator + fileBookSt); if(fileOfBook.exists()){ buttonDownload.setEnabled(false); } buttonDownload.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Type itemsListType = new TypeToken<List<String>>() { }.getType(); String folderB = "bookfiles_" + bookId; String fileBookStorage = "book_" + bookId + ".json"; BookLoader bookLoader = new BookLoader(); bookLoader.execute(); ArrayList<String> pagesPath; ArrayList<String> soundsPath; soundsPath = new ArrayList<>(); File bookfolder = new File(String.valueOf(getExternalFilesDir(folderB))); if (!bookfolder.exists()) { bookfolder.mkdirs(); Log.d("my", "dir. created"); } try { String result = bookLoader.get(); Gson gson = new Gson(); Book book = gson.fromJson(result, Book.class); List<String> pages = book.getPageUrl(); String[] urlsPages = pages.toArray(new String[0]); FileLoader fileLoader = new FileLoader(); fileLoader.execute(urlsPages); String flResult = fileLoader.get(); pagesPath = new Gson().fromJson(flResult, itemsListType); BookFiles bookFiles = new BookFiles(); bookFiles.setBookID(bookId); bookFiles.setPagesPath(pagesPath); bookFiles.setSoundsPath(soundsPath); Gson gson11 = new Gson(); String filesJson = gson11.toJson(bookFiles); MyJSON.saveData(getApplicationContext(), filesJson, fileBookStorage); } catch (InterruptedException | ExecutionException e) { e.printStackTrace(); } // } } }); buttonRead.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { NextActivity(); } }); } private class BookLoader extends AsyncTask<Void, Void, String> { HttpURLConnection urlConnection = null; BufferedReader reader = null; String resultJsonBook = ""; private String bookIdJson = "http://*****.ru/todbook/book" + bookId + ".json"; @Override protected String doInBackground(Void... voids) { try { URL url = new URL(bookIdJson); urlConnection = (HttpURLConnection) url.openConnection(); urlConnection.setRequestMethod("GET"); urlConnection.connect(); InputStream inputStream = urlConnection.getInputStream(); StringBuffer buffer = new StringBuffer(); reader = new BufferedReader(new InputStreamReader(inputStream)); String line; while ((line = reader.readLine()) != null) { buffer.append(line); } resultJsonBook = buffer.toString(); } catch (Exception e) { e.printStackTrace(); } return resultJsonBook; } @Override protected void onPreExecute() { super.onPreExecute(); } } private class FileLoader extends AsyncTask<String, Void, String> { Fetch mFetch; String folderB = "bookfiles_" + bookId; File bookfolder = new File(String.valueOf(getExternalFilesDir(folderB))); List<Request> requestListPages = new ArrayList<>(); ArrayList<String> pagesPath = new ArrayList<>(); String resultD; @Override protected String doInBackground(String... urlsFiles) { mFetch = Fetch.newInstance(getApplicationContext()); mFetch.removeRequests(); //чистим Π±Π°Π·Ρƒ запросов for (int i = 0; i < urlsFiles.length; i++) { String url = urlsFiles[i]; String path = String.valueOf(bookfolder); String fileName = Uri.parse(url).getLastPathSegment(); Log.d("my2", fileName); Request request = new Request(url, path, fileName); requestListPages.add(request); String pageFilePath = path + "/" + fileName; Log.d("my2", pageFilePath); pagesPath.add(pageFilePath); } mFetch.enqueue(requestListPages); // resultD = String.valueOf(pagesPath); String resultD = new Gson().toJson(pagesPath); return resultD; } } private void BookUriFromId() { //ΠΏΠΎΠ»ΡƒΡ‡Π°Π΅ΠΌ Π½ΠΎΠΌΠ΅Ρ€ ID ΠΊΠ½ΠΈΠ³ΠΈ, с ΠΎΠ±Π»ΠΎΠΆΠΊΠΈ ΠΊΠΎΡ‚ΠΎΡ€ΠΎΠΉ ΠΏΠ΅Ρ€Π΅ΡˆΠ»ΠΈ Π² слайдСр Intent intent = getIntent(); bookId = intent.getIntExtra("bookId", 1); Log.d(TAG, "You read book β„–" + bookId); } private void NextActivity() { new Handler().postDelayed(new Runnable() { @Override public void run() { Intent intent = new Intent(BookCardActivity.this, SliderActivity.class); intent.putExtra("bookId", bookId); // ΠΏΠ΅Ρ€Π΅Π΄Π°ΡŽ Π² слайдСр Π½ΠΎΠΌΠ΅Ρ€ ΠΊΠ½ΠΈΠ³ΠΈ startActivity(intent); finish(); } }, 20); } private ArrayList<String> getFilesPathFromFile(String jsResult) { ArrayList<String> urisImg = new ArrayList<>(); try { JSONArray rootJson = new JSONArray(new JSONTokener(jsResult)); for (int i = 0; i < rootJson.length(); i++) { JSONObject o = rootJson.getJSONObject(i); String strTo = (String) o.get("uriString"); urisImg.add(strTo); } } catch (JSONException e) { e.printStackTrace(); } return urisImg; } }

    1 answer 1

    What did you write the AsyncTask , and call them synchronously in the UI-thread ( View.OnClickListener )

     String result = bookLoader.get(); ... String flResult = fileLoader.get();

    Then there is no point even to look, everything needs to be rewritten.

    PS It seems that your past C # experience is bothering you, there is a similarity of await/async for Android only in Kotlin-e.

    • Can you please tell me how to implement this scheme: parse json from the server, create an ArrayList object from it with the url of files on the server, then load the files through the list? In one AsynkTask I can’t do it ... - Vyacheslav
    • And you do not need AsyncTask for this. It was invented for the scheme: taken from the UI -> processed / downloaded -> returned to the UI. If there is no last interaction with the UI, then do everything on the usual Runnable, which can be sent for execution to both the normal Thread and Executor, at least sequentially, at least in parallel, even though at once, even with a delay. - Eugene Krivenja