AsyncTask 中的 ProgressDialog

Question

我在 AsyncTask 中使用 ProgressDialog 时遇到问题。

在onPreExecute()中我启动ProgressDialog，但是当我在onPosTExecute()中完成ProgressDialog时出现错误

Cannot resolve symbol 'progresso'

这是我的代码：

 private class DataTransfer extends AsyncTask<Void, Integer, String> {
    private ProgressDialog progresso;
    @Override
    protected void onPreExecute()
    {

        super.onPreExecute();

        progresso.setIndeterminate(true);
        progresso.setCancelable(false);
        progresso.setMessage("Your message");
        progresso.show();
    }


    protected String doInBackground(Void... params) {

        return postData();
    }


    public String postData() {
        String origresponseText = "";
        // Create a new HttpClient and Post Header
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("*****"); //URL here
        try {
            // Add your data
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
            nameValuePairs.add(new BasicNameValuePair("teste", "OK"));
            nameValuePairs.add(new BasicNameValuePair("crc", "010101"));
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

            // Execute HTTP Post Request
            HttpResponse response = httpclient.execute(httppost);

            origresponseText = readContent(response);

        } catch (ClientProtocolException e) {
            Log.i("ClientProtocolException", e.toString());
            cancel(true);
        } catch (IOException e) {
            Log.i("IOException", e.toString());
            cancel(true);
        }

           String responseText = origresponseText;
        Log.i("String", responseText);
           return responseText;

    }

    public String readContent(HttpResponse response) {
        String text = "";
        InputStream in = null;
        try {
            in = response.getEntity().getContent();
            BufferedReader reader = new BufferedReader(new InputStreamReader(in));
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line).append("\n");
            }
            text = sb.toString();
        } catch (IllegalStateException | IOException e) {
            e.printStackTrace();

        } finally {
            try {

                in.close();
            } catch (Exception ex) {
            }
        }

        return text;
    }


    protected void onCancelled(String result) {
        Log.i("Async", "Cancelled");
    }



@Override
    private void onPostExecute(String result) {
        // showDialog("Downloaded " + result + " bytes");


    progresso.dismiss();
        Log.i("Async", "PostExecute");
        Log.i("Result", result);

    }

}

Answer 1

在onPreExecute()，你有

progresso

你已经在上面这样声明了

private ProgressDialog progresso;

但是在onPostExecute() 你有

progressBar

只需将其更改为

@Override
private void onPostExecute(String result) {
    // showDialog("Downloaded " + result + " bytes");

    progresso.dismiss();

Answer 2

编辑：

您没有在任何地方初始化进度对话框。使用前先构造：

progressBar = new ProgressDialog(YourActivityName.this);

文档是here。

Answer 3

关于第一个问题，这是一个书写错误，在 stackoverflow 中。我将“progressBar”用于ProgressDialog，然后，在编辑主题时，我编辑并通过“progress”更改了“progressBar”，但忘记更改onPostExecute。在我的原始代码中，我使用了“progressBar”。已经在帖子中修复了。

编辑：我现在感觉很愚蠢。我发现了错误。我把“OnPostExecute()”放在“DataTransfer”类之外，甚至没有意识到。很抱歉给您带来不便，感谢您的帮助。

Answer 4

你还没有初始化你的进度对话框..这里是更新代码

    private class DataTransfer extends AsyncTask<Void, Integer, String> {
    private ProgressDialog progresso;
    @Override
    protected void onPreExecute()
    {

        super.onPreExecute();
        progresso =new ProgessDialog(MainActivity.this);
        progresso.setIndeterminate(true);
        progresso.setCancelable(false);
        progresso.setMessage("Your message");
        progresso.show();
    }


    protected String doInBackground(Void... params) {

        return postData();
    }


    public String postData() {
        String origresponseText = "";
        // Create a new HttpClient and Post Header
        HttpClient httpclient = new DefaultHttpClient();
        HttpPost httppost = new HttpPost("*****"); //URL here
        try {
            // Add your data
            List<NameValuePair> nameValuePairs = new ArrayList<NameValuePair>(2);
            nameValuePairs.add(new BasicNameValuePair("teste", "OK"));
            nameValuePairs.add(new BasicNameValuePair("crc", "010101"));
            httppost.setEntity(new UrlEncodedFormEntity(nameValuePairs));

            // Execute HTTP Post Request
            HttpResponse response = httpclient.execute(httppost);

            origresponseText = readContent(response);

        } catch (ClientProtocolException e) {
            Log.i("ClientProtocolException", e.toString());
            cancel(true);
        } catch (IOException e) {
            Log.i("IOException", e.toString());
            cancel(true);
        }

           String responseText = origresponseText;
        Log.i("String", responseText);
           return responseText;

    }

    public String readContent(HttpResponse response) {
        String text = "";
        InputStream in = null;
        try {
            in = response.getEntity().getContent();
            BufferedReader reader = new BufferedReader(new InputStreamReader(in));
            StringBuilder sb = new StringBuilder();
            String line = null;
            while ((line = reader.readLine()) != null) {
                sb.append(line).append("\n");
            }
            text = sb.toString();
        } catch (IllegalStateException | IOException e) {
            e.printStackTrace();

        } finally {
            try {

                in.close();
            } catch (Exception ex) {
            }
        }

        return text;
    }


    protected void onCancelled(String result) {
        Log.i("Async", "Cancelled");
    }



@Override
    private void onPostExecute(String result) {
    progresso.dismiss();
        Log.i("Async", "PostExecute");
        Log.i("Result", result);

    }

}