Question

我想显示正在读取文件并放入数组列表的进度。这样，在应用程序以列表视图的形式向用户显示数组列表之前，我想展示通过AsyncTask读取了多少文件。当前，白屏短暂显示。正在读取的文件大约有20000行。

AsyncTask（MyTask）是通过onCreate()方法执行的，如下所示：

 private class MyAsync extends AsyncTask<Void, Integer, ArrayList<Movie>> {
    ProgressDialog mProgressDialog;
    ArrayList<Movie> movies;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();

        //Show progress to user
        mProgressDialog = new ProgressDialog(MovieRatingsActivity.this);
        mProgressDialog.setTitle("Reading file");
        mProgressDialog.setMessage("Reading file, Please Wait!");
        mProgressDialog.setIndeterminate(false);
        mProgressDialog.setProgressStyle(ProgressDialog.STYLE_HORIZONTAL);
        mProgressDialog.show();
    }

    @Override
    protected ArrayList<Movie> doInBackground(Void... voids) {

        try {
            InputStream inputStream = getResources().openRawResource(R.raw.ratings);
            int count = inputStream.available();

            // onProgressUpdate( (amount read by inputstream / size of file )* 100 );

            movies = Movie.loadFromFile(inputStream);
            return movies;

        } catch (Exception e) {
            e.printStackTrace();
        }

        return null;
    }

    @Override
    protected void onProgressUpdate(Integer... progress) {
        super.onProgressUpdate(progress);
        mProgressDialog.setProgress(progress[0]);
    }

    @Override
    protected void onPostExecute(ArrayList<Movie> movies) {
        super.onPostExecute(movies);
        mProgressDialog.dismiss();

        mInflater = (LayoutInflater) getApplicationContext().getSystemService(Context.LAYOUT_INFLATER_SERVICE);
        setListAdapter(new RowIconAdapter(getApplicationContext(), R.layout.listrow, R.id.row_label, movies));
    }
}

函数Movie.loadFromFile(inputStream)-将数据放入数组列表的位置

    /** Loads movie information from a raw resource file */
public static ArrayList<Movie> loadFromFile(InputStream inputStream) {
    ArrayList<Movie> movies = new ArrayList<Movie>(20000);
    BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
    String line;
    try {
        while ((line = br.readLine()) != null) {
            String lRatings = line.substring(0,3).trim();
            String lVotes = line.substring(4,12).trim();
            String lName = line.substring(13).trim();
            movies.add(new Movie(lName, lRatings, lVotes));
        }
    } catch (IOException iox) { } // pure evil at work
    return movies;
}

Answer 1

在doInBackground()内部调用publishProgress(value)，其中value是一个整数，代表完成的工作百分比。
这将触发onProgressUpdate()，您将在progress[0]中获得先前传递的值，然后可以相应地更新进度条。
编辑只能在while的{{1}}循环中计算完成的工作百分比。因此，在这种情况下，更容易删除loadFromFile()并将其所有代码放入loadFromFile()中。然后像这样修改循环：

doInBackground()

值int counter = 0; while ((line = br.readLine()) != null) { String lRatings = line.substring(0,3).trim(); String lVotes = line.substring(4,12).trim(); String lName = line.substring(13).trim(); movies.add(new Movie(lName, lRatings, lVotes)); counter++; if ((counter % 200) == 0) publishProgress(counter / 200) }将占完成工作的1％，但您可以在耗时的情况下进行更改

使用AsyncTask显示输入流文件的读取进度

1 个答案: