异步错误＆QUOT;当前线程必须有一个活套＆QUOT;点击重试按钮时 [英] Async error "Current thread must have a looper" when clicking retry button

问题描述

我有一个应用程序从一个网站读取一些数据，然后对什么是从网站中检索创建 TextViews 。我有这个过程通过的AsyncTask 工作。我知道了建立，因此如果在试图从网站看网络错误，会显示一个重试按钮。我的code完美的作品时，它贯穿于第一次，但是当我尝试从按钮的的onClick 的code，我得到以下错误：

I have an app that reads some data from a website and then creates TextViews for what is retrieved from the website. I have the process working through an AsyncTask. I've got it set up so that if there is a network error while trying to read from the website, a Retry button is shown. My code works perfect when it runs through the first time, but when I try to run the code from the onClick of the button, I get the following error:

java.lang.RuntimeException: An error occured while executing doInBackground()
    (a few lines of error code)
Caused by: java.lang.IllegalStateException: The current thread must have a looper!

我什至有的onClick 调用外部方法，我看到有人建议，但是这并没有帮助。下面是一些相关的code的：

I even tried to have the onClick call an outside method as I saw someone recommend, but that didn't help. Here is some of the relevant code:

异步任务

private class DownloadListingTask extends AsyncTask<String, Void, String>{
    @Override
    protected String doInBackground(String... urls){
        showLoadingPage();
        try{
            return getList(urls[0]);
        }
        catch (IOException e){
            return sharedPreferences.getString("list_cache", "");
        }
    }

    @Override
    protected void onPostExecute(String result){
        formatList(result);
    }
}

调用方法

private void tryDownload(){
    DownloadListingTask downloadListingTask = new DownloadListingTask();
    downloadListingTask.execute(url);
}

onClick事件

retryButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                tryDownload();
            }
        });

所以，当 tryDownload（）方法是从 onCreateView 称它工作得很好，但是当我尝试从在的onClick 是当我得到这个错误。

So when the tryDownload() method is called from onCreateView it works fine, but when I try it from the onClick is when I get that error.

推荐答案

试图调用showLoadingPage在preExecute方式：

Try to call showLoadingPage in onPreExecute method:

private class DownloadListingTask extends AsyncTask<String, Void, String>{
    @Override
    protected void onPreExecute(){
          showLoadingPage();
    }
    @Override
    protected String doInBackground(String... urls){
        try{
            return getList(urls[0]);
        }
        catch (IOException e){
            return sharedPreferences.getString("list_cache", "");
        }
    }

    @Override
    protected void onPostExecute(String result){
        formatList(result);
    }
}

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