android - asynctask，progressbar和I / O. [英] android - asynctask, progressbar and I/O

问题描述

我很抱歉将相似的问题发布到我之前的问题上，但我无法解决这个问题。

I'm sorry for posting similar question to my previous one, but I just can't figure this out.

我一直在使用简单的ping示例我发现这里，只是想添加ProgressBar，但没有运气。我真的不明白发生了什么。

I've been using simple "ping" example I found here and just wanted to add ProgressBar but with no luck. I really don't understand what's going on.

所以，这很好用：

    protected void onPreExecute() {
    sb = new StringBuilder();
    mPOut = new PipedOutputStream();
    try {
        mPIn = new PipedInputStream(mPOut);
        mReader = new LineNumberReader(new InputStreamReader(mPIn));
    } catch (IOException e) {
        cancel(true);
    }
    //myBar.setVisibility(View.VISIBLE); -> PROBLEM!!!
}

protected Object doInBackground(Object... arg0) {
    try {
        process = Runtime.getRuntime().exec("ping -c 4 " + ipadd);
        InputStream in = process.getInputStream();
        OutputStream out = process.getOutputStream();
        byte[] buffer = new byte[1024];
        int count;
        while ((count = in.read(buffer)) != -1) {
            mPOut.write(buffer, 0, count);
            String bs= new String(buffer);
            publishProgress(); 
        }
        in.close();
        out.close();
        mPOut.close();
        mPIn.close();
    } catch (IOException e) {
    }
    return null;
}

protected void onPostExecute(Object result) {
            myBar.setVisibility(View.INVISIBLE);
            tv.setText(sb);
            System.out.println(sb);
}

我从ping获得输出，myBar显然没有显示，因为它是隐形的第一名。

I get output from ping, myBar is obviously not diplayed since it is invisible in the first place.

如果我从标记为问题的行中删除注释（将进度条可见性设置为可见），我只是没有得到ping的输出。我似乎以某种方式弄乱了我的I / O或其他东西。 ProgressBar在结尾显示并隐藏，但没有输出。

If I remove the comment from the line I marked as a problem (set progress bar visibility to visible), I simply get no output from ping. I seems that it somehow messes up my I/O or something. ProgressBar is displayed and hidden at the end, but no output.

我真的无法弄清楚这一点，所以如果你有任何想法，我真的很感激任何帮助。

I really can't figure this out, so if you have any idea, I would really appreciate any help.

谢谢!!!

推荐答案

尝试以编程方式创建ProgressDialog在OnPreExecute（）方法中，一旦在onPostExecute（）中完成任务就将其解除。这是一个代码：

Try to create programmatically a ProgressDialog in OnPreExecute() method and dismiss it once task is finished in onPostExecute(). Here is a code:

add to onPreExcute:
    super.onPreExecute();
    ProgressDialog pDialog = new ProgressDialog(YourActivity.this);
        pDialog.setMessage("Please wait...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(false);
        pDialog.show();

add to onPostExecute:
   pDialog.dismiss();

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