对于某些任务，AsyncTask的doInBackground（）不执行（尽管有新的实例化）

Question

这个错误很常见，但尽管应用了最受欢迎的解决方案几天，我仍然陷入困境。我有几个扩展AsyncTask的类。

奇怪的是我的PostComment.java会调用doInBackground但DownloadComments.java不会，尽管它们一个接一个地处于同一个函数中。我调用执行的顺序无关紧要。

Bios.java 调用DownloadComments和PostComment

@Override
public void onClick(View v) {
    switch(v.getId()) {
        case(R.id.Post):

        // Start DownloadComments
        // Execute doInBackground NOT CALLED
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            new DownloadComments().executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, "Clinton");
        } else {
            new DownloadComments().execute(candidate);
        }

        // Post Comment
        EditText commentHandler = (EditText) findViewById(R.id.comment);
        String commentString = commentHandler.getText().toString();
        // Execute doInBackground IS CALLED
        if(Build.VERSION.SDK_INT >= Build.VERSION_CODES.HONEYCOMB) {
            new PostComment().executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, commentString, MainActivity.username, Integer.toString(MainActivity.PosterID));
        } else {
            new PostComment().execute(commentString, MainActivity.username, Integer.toString(MainActivity.PosterID));
        }
        break;
    default:
        break;
    }
}

PostComment.java（extends AsyncTask<String, Void, Void>）

@Override
protected Void doInBackground(String... arg0) {
    // Otherwise SocketException Connection reset by peer
    try {
        String comment = arg0[0];
        String username = arg0[1];
        String PosterName = arg0[2];


        // EDIT LINK
        String link = "http://particlecollider.net76.net/postComment.php";


        URL url = new URL(link);
        String data = URLEncoder.encode("comment", "UTF-8") + "="
                + URLEncoder.encode(comment, "UTF-8")
                + "&"
                + URLEncoder.encode("UN", "UTF-8") + "="
                + URLEncoder.encode(username, "UTF-8");
        URLConnection conn = url.openConnection();

        System.setProperty("http.keepAlive", "false");
        // Kill keep-alive property
        conn.setRequestProperty("connection", "close");


        // Write
        conn.setDoOutput(true);
        OutputStreamWriter wr = new OutputStreamWriter(conn.getOutputStream());

        wr.write(data);
        wr.flush();

        // Read
        BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));

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

下载评论extends AsyncTask<String, Void, String>此方法并未全部输入

@Override
protected String doInBackground(String... passedIn) {
    try {
        String candidate = passedIn[0];
        String link = "http://particlecollider.net76.net/downloadComments.php?candidate="+candidate;
        int CommentsInLinearList;

    URL url = new URL(link);
    URLConnection conn = url.openConnection();

    System.setProperty("http.keepAlive", "false");
    // Kill keep-alive property
    conn.setRequestProperty("connection", "close");

    BufferedReader reader = new BufferedReader(new InputStreamReader(conn.getInputStream()));

    StringBuilder sb = new StringBuilder();
    String line = null;

    // Read Server Response
    // Skip until it works
    while (!(line = reader.readLine()).contains("COMMENTLINEARLIST")) {
        // Finished
    }
    CommentsInLinearList = Integer.parseInt(reader.readLine());
    while (CommentsInLinearList > 0) {
        line = reader.readLine();
        sb.append(line);
        CommentsInLinearList--;
    }

    JSONObject jObject = new JSONObject(sb.toString());
    JSONArray myJSONArray = jObject.getJSONArray("CommentLinearList");
    if(myJSONArray != null) {
        for(int i=0; i<myJSONArray.length(); i++) {
            JSONObject targetComment = myJSONArray.getJSONObject(i);
            Comment PushComment = new Comment(candidate);
            PushComment._ID = Integer.parseInt(targetComment.getString("ID"));
            PushComment._Candidate = candidate;
            PushComment._PosterID = Integer.parseInt(targetComment.getString("PosterID"));
            PushComment._ReplyToId = Integer.parseInt(targetComment.getString("ReplyToID"));
            PushComment._Rating = Integer.parseInt(targetComment.getString("Rating"));
            PushComment._Comment = targetComment.getString("Comment");
            // PushComment into candidateCommentArrayList
            candidateCommentArrayList.add(PushComment);
        }
        // getMenuInflater().inflate(R.menu., candidateCommentArrayList);
    }
    return sb.toString();
} catch (Exception e) {
    e.printStackTrace();
}

return null;
}

调试时，它甚至不会为DownloadComments输入doInBackground

请帮忙。如果我可以添加更多详细信息，请告诉我