Indeterminate ProgressBar not showing during AsyncTask operation

Question

I have a GoogleTranslate.java file that has a class, GoogleTranslate, that extends AsyncTask. The purpose of this task is to perform Google translations.

I have another class, MyVocab, that allows the user to input a word to translate in an alert dialog. So on a click to the alert dialog button, the word will be translated to the desired language by calling on the GoogleTranslate class. However, when I pass a progress bar from MyVocab to GoogleTranslate it doesn't work. When the operation is running (for an observable amount of time), the progress bar doesn't show. I set the progress bar as VISIBLE in onPreExecute and set it as GONE in onPostExecute.

I'm wondering if it's because I have GoogleTranslate and MyVocab in two different java files since most of the examples I see have async class and the class that calls it in the same java file. Please let me know if there's anything I'm doing wrong that's causing this problem.

Here's the related code:

GoogleTranslate.java

public class GoogleTranslate extends AsyncTask<String, Void, String>{

private ProgressBar mProgressBar;

public GoogleTranslate(ProgressBar progressBar) {
    super();
    mProgressBar = progressBar;
}

@Override
protected void onPreExecute() {
    mProgressBar.setVisibility(View.VISIBLE);
}

@Override
protected void onPostExecute(String s) {
    mProgressBar.setVisibility(View.GONE);
}

@Override
protected String doInBackground(String... params) {
    String vocab = params[0];
    String source = params[1];
    String target = params[2];

    String sourceQuery = "";
    String targetQuery = "&target=" + target;

    // "" means its
    if (!source.equals("Detect Language")) {
        sourceQuery = "&source=" + source;
    }

    try {
        String APIKey = "MY_API_KEY";
        String encodedQuery = URLEncoder.encode(vocab, "UTF-8");
        URL url = new URL("https://www.googleapis.com/language/translate/v2?key=" +
                APIKey +
                "&q=" +
                encodedQuery +
                sourceQuery +
                targetQuery);
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
        try {
            BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
            StringBuilder stringBuilder = new StringBuilder();
            String line;
            while ((line = bufferedReader.readLine()) != null) {
                stringBuilder.append(line).append("\n");
            }
            bufferedReader.close();
            return stringBuilder.toString();
        }
        finally {
            urlConnection.disconnect();
        }
    }
    catch (Exception e) {
        return null;
    }
}

}

Parts of method from MyVocab:

protected void addVocabAlertDialog(final VocabDbHelper dbHelper, final String category,
                                 final VocabCursorAdapter cursorAdapter) {
    AlertDialog.Builder builder = new AlertDialog.Builder(this);
    builder.setTitle("Add Vocab");

    LayoutInflater li = LayoutInflater.from(CategoryItem.this);
    View promptsView = li.inflate(R.layout.alert_dialog_add_vocab, null);
    final EditText vocabInput = (EditText) promptsView.findViewById(R.id.vocabInput);
    final EditText definitionInput = (EditText) promptsView.findViewById(R.id.definitionInput);
    final ProgressBar progressBar = (ProgressBar) promptsView.findViewById(R.id.progressBar);
    builder.setView(promptsView);

    final GoogleTranslate googleTranslate = new GoogleTranslate(progressBar);
    // Set up the buttons
    builder.setPositiveButton("OK", new DialogInterface.OnClickListener() {
        @Override
        public void onClick(DialogInterface dialog, int which) {
            String vocab = vocabInput.getText().toString();
            String definition = definitionInput.getText().toString();
            dbHelper.insertVocab(category, vocab, definition, 0);
            if (!category.equals(VocabDbContract.CATEGORY_NAME_MY_WORD_BANK)) {
                dbHelper.insertVocab(VocabDbContract.CATEGORY_NAME_MY_WORD_BANK, vocab, definition, 0);
            }
            // Update Cursor
            Cursor cursor = dbHelper.getVocabCursor(category);
            cursorAdapter.changeCursor(cursor);
        }
    });
    final AlertDialog dialog = builder.create();

    dialog.show();

    dialog.getButton(AlertDialog.BUTTON_NEUTRAL).setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            String vocab = vocabInput.getText().toString();

            SharedPreferences sharedPreferences = getSharedPreferences("Translation", MODE_PRIVATE);
            int sourcePos = sharedPreferences.getInt("Source", 0); // 0 is for Detect Language
            int targetPos = sharedPreferences.getInt("Target", 19); // 19 is for English

            String source = LanguageOptions.FROM_LANGUAGE_CODE[sourcePos];
            String target = LanguageOptions.TO_LANGUAGE_CODE[targetPos];

            final AlertDialog.Builder builder = new AlertDialog.Builder(CategoryItem.this);
            builder.setMessage("Network is unavailable. Please try again later.");
            builder.setNegativeButton("OK", new DialogInterface.OnClickListener() {
                @Override
                public void onClick(DialogInterface dialog, int which) {
                    dialog.cancel();
                }
            });
            AlertDialog dialog = builder.create();

            if (isNetworkAvailable()) {
                AsyncTask<String, Void, String> asyncTask = googleTranslate.execute(vocab, source, target);
                try {
                    String translatedJSON = asyncTask.get();
                    JSONParser jsonParser = new JSONParser();
                    String translatedText = jsonParser.parseJSONForTranslation(translatedJSON);
                    definitionInput.setText(translatedText);
                } catch (Exception e) {
                    dialog.show();
                }
            }
            else {
                dialog.show();
            }
        }
    });

}

XML file that contains progress bar:

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:orientation="vertical">

<EditText
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:hint="Vocab"
    android:id="@+id/vocabInput"
    android:inputType="textAutoComplete"/>

<EditText
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:hint="Definition"
    android:id="@+id/definitionInput"
    android:inputType="textAutoComplete"
    android:layout_below="@+id/vocabInput"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

<ProgressBar
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:layout_centerInParent="true"
    android:visibility="gone"
    android:indeterminate="true"
    android:id="@+id/progressBar"/>

Answer 1

I'd suggest using ProgressDialog instead.

I switched from ProgressBar because I faced a similar issue, even after programmatically creating one in the default constructor of my AsyncTask.

public class GoogleTranslate extends AsyncTask<String, Void, String> {
    private ProgressDialog mProgressDialog;
    private Context mContext;

    public GoogleTranslate(Context context) {
        mContext = context;
    }

     @Override
     protected void onPreExecute() {

         mProgressDialog = ProgressDialog.show(
                mContext,
                "Please wait", // Title
                "Translating", // Message
                true           // Indeteriminate flag
         );
     }

     @Override
     protected String doInBackground(String... params) {
         ...
     }

     @Override
     protected void onPostExecute(String s) {
         if (mProgressDialog != null) {
              mProgressDialog.dismiss();
         }
         ...
     }
 }

Call this AsyncTask like this:

new GoogleTranslate(getActivity() /* or getContext() */).execute(vocab, source, target);

Answer 2

add this before executing the googleTranslate :

 progressBar.setVisibility(View.VISIBLE);
 progressBar.setProgress(0);
 AsyncTask<String, Void, String> asyncTask = googleTranslate.execute(vocab,source, target);

and also implement the onProgressUpdate in googleTranslate.

this link may help :

http://www.concretepage.com/android/android-asynctask-example-with-progress-bar

Answer 3

Try to avoid the AsyncTask get() method and use a listener instead. You should update your code this way:

1) In your googleTranslate class, add a listener:

private Listener listener;

    public interface Listener{
        void onTaskResult(String string);
    }

    public void setListener(Listener listener){
        this.listener = listener;
    }

and call it in your onPostExecute:

 @Override
    protected void onPostExecute(String s) {
        if (listener!=null){ listener.onTaskResult(s); }
                mProgressBar.setVisibility(View.GONE);

    }

2) update your main class replacing the get with the listener management, replacing this:

AsyncTask<String, Void, String> asyncTask = googleTranslate.execute(vocab, source, target);
                try {
                    String translatedJSON = asyncTask.get();
                    JSONParser jsonParser = new JSONParser();
                    String translatedText = jsonParser.parseJSONForTranslation(translatedJSON);
                    definitionInput.setText(translatedText);
                } catch (Exception e) {
                    dialog.show();
                }

with this:

googleTranslate.setListener(new GoogleTranslate.Listener() {
            @Override
            public void onTaskResult(String string) {
                    String translatedJSON = string;
                    JSONParser jsonParser = new JSONParser();
                    String translatedText = jsonParser.parseJSONForTranslation(translatedJSON);
                    definitionInput.setText(translatedText);
            }
        });
        googleTranslate.execute(vocab, source, target);

I hope it helped.

Answer 4

Try passing ProgressBar as constructor argument of GoogleTranslate class.

Answer 5

Add progress bar in your onPreExecute method and hide it in onPostExecute.

private class MyAsyncThread extends AsyncTask<Void, Void, String>
{
            @SuppressWarnings("finally")

            @Override
            protected String doInBackground(Void... params) {
                // TODO Auto-generated method stub
                try {

                // your code

                }
                catch (Exception e) {
                    // TODO: handle exception
                }
                finally
                {

                    return "OK";

                }

            }
            @Override
            protected void onPostExecute(String result) {
                // TODO Auto-generated method stub
                super.onPostExecute(result);

               if (progressDialog != null) {
                   progressDialog.dismiss();
                   progressDialog = null;
               }

                        }catch (Exception e) {
                            // TODO: handle exception
                            e.printStackTrace();
                        }
            }


            @Override
            protected void onPreExecute() {
                super.onPreExecute();
                progressDialog = ProgressDialog.show(this, null, "Please wait....");
            }

Answer 6

That's because you are blocking Main Thread by asyncTask.get() call, so no UI operations can run until asyncTask completes.

Remove this call and process the asyncTask's results in its onPostExecute(String s) and onCancelled() callbacks instead.