AsyncTask on ftp project

Question

I have problem with asynctasks blocking UI when task download metafile from FTP server.

[Main.class] FragmentActivity

@Override
    public void onClick(View view) {

        TestSettings(); // TODO do usunięcia z kodu
        String password = this.password.getText().toString();

        boolean isConnected = false;

        try {
            isConnected = new TaskConnect(new ProgressDialog(getActivity().getApplicationContext()), password).execute().get();
        } catch (InterruptedException e) {
            e.printStackTrace();
        } catch (ExecutionException e) {
            e.printStackTrace();
        }

        if (isConnected) {

            Toast.makeText(getActivity(), "Connected", Toast.LENGTH_LONG).show();

            try {

                boolean isListDownloaded = new TaskDownloadFilesList(new ProgressDialog(getActivity().getApplicationContext())).execute().get();

                if(isListDownloaded) {
                    getFragmentManager().beginTransaction()
                            .replace(R.id.container, new FragmentList(client.getList()))
                            .addToBackStack(this.getTag())
                            .commit();
                }

            } catch (InterruptedException e) {
                e.printStackTrace();
            } catch (ExecutionException e) {
                e.printStackTrace();
            }


        }


    }

[TaskDownloadFilesList.class] - AsyncTask

public class TaskDownloadFilesList extends AsyncTask <Boolean, Boolean, Boolean> {

    private static final FTP CLIENT = FTP.getInstance();
    private static ProgressDialog dialog = null;
    private static boolean isDownloaded = false;

    public TaskDownloadFilesList(ProgressDialog dialog) { this.dialog = dialog; }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        dialog.setMessage("Downloading list");
        dialog.setCancelable(false);
    }

    @Override
    protected Boolean doInBackground(Boolean... booleans) {

        dialog.show();

        if(CLIENT.isConnected()) {
            try { isDownloaded = CLIENT.checkList(); }
            catch (IOException e) { e.printStackTrace(); }
        }

        return false;
    }

    @Override
    protected void onPostExecute(Boolean aBoolean) {
        super.onPostExecute(aBoolean);
        dialog.dismiss();
    }

    public boolean getResult() {
        return isDownloaded;
    }

In fact I use TaskConnect to connect to the FTP Server this task not freeze UI.

score 1 · Accepted Answer · answered Jan 26 '14 at 16:16

1

You are calling AsyncTask's get() which blocks the calling Thread until it finishes. Remove the get() calls.

answered Jan 26 '14 at 16:16

Emmanuel

13,083
4
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I use Task to connecting and its not blocked UI, how to get information when job is done ? – Nerus Jan 26 '14 at 16:19
the `get()` will block the calling `Thread`. What you want to do is call `execute()`, do the long running task in `doInBackground()` and return the value that will be passed to `onPostExecute()` so you can update the UI `Thread` – Emmanuel Jan 26 '14 at 16:21
@Nerus information when job is done can be obtained in `onPostExecute()` method of asynctask, look at my answer. – S.Thiongane Jan 26 '14 at 16:22
As Emmanuel said, `.get()` blocks the `UI`. If the task is an inner-class of the `Activity` then you can call an `Activity` function, update a variable, or whatever you need in `onPostExecute()` which will be called when `doInBackground()` finishes. If the `AsyncTask` is a separate file then [see this answer about using an interface](http://stackoverflow.com/questions/18517400/inner-class-can-access-but-not-update-values-asynctask/18517648#18517648) to pass a callback from `onPostExecute()` when the task finishes – codeMagic Jan 26 '14 at 16:26
@Emmanuel : `onPostExecute(Result), invoked on the UI thread after the background computation finishes.` from [here](http://developer.android.com/reference/android/os/AsyncTask.html) – S.Thiongane Jan 26 '14 at 16:27
1) I don't need to look at your answer to provide one which is so obvious. Look at the two answers and see if they are identicals 2) I don't need to redirect you to my answer, it's just because i gave him directly what he wanted, oppositly to you (your solution is between comments, not in your answer). – S.Thiongane Jan 26 '14 at 18:31

score 1 · Answer 2 · answered Jan 26 '14 at 16:18

1

Instead of using get() method of AsyncTask, you may wait that task finish in doInBackground() method then add the code you want to execute in onPostExecute().

answered Jan 26 '14 at 16:18

S.Thiongane

6,883
3
37
52

AsyncTask on ftp project

2 Answers2