Question

我有一个主要活动有2个AsyncTask，我希望其中一个AsyncTask中止另一个AsyncTask。

class Contador extends AsyncTask<String, String, String>{

@Override
protected void onPreExecute() {

    }

@Override
protected String doInBackground(String... params) {
// TODO Auto-generated method stub
     try {
            httpclientContador = new DefaultHttpClient();

            String sContador = "http://webmilab.com/SEDESOL/index.php/transferencias/conteo/" + resIdEncuesta;

            pContador = new HttpPost(sContador);


            pContador.addHeader("content-type", "application/x-www-form-urlencoded");
            JSONObject jContador = new JSONObject();
            jContador.put("mensaje", "Empezar a contar :)");

            StringEntity eContador = new StringEntity("json="+jContador.toString(), "UTF-8");
            pContador.setEntity(eContador);
            httpclientContador.execute(pContador);


        } catch (IOException e) {
            e.printStackTrace();
            Toast.makeText(TransferirDatos.this, "Hubo un error al realizar la petición del conteo", Toast.LENGTH_LONG).show();

        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }


        return null;
    }

    protected void onPostExecute(String file_url) { 

        }

    }

}

这是我想要完成的AsyncTask。

class Contador extends AsyncTask<String, String, String>{

    @Override
    protected void onPreExecute() {
    }

    @Override
    protected String doInBackground(String... params) {
        // TODO Auto-generated method stub

        //Some Code

        return null;
    }

    protected void onPostExecute(String file_url) { 

        pContador.abort();  

    }

}

HttpPost pContador和HttpClient httpclientContador是主要活动中定义的变量。

当我尝试执行此代码时，应用程序始终崩溃，我想知道如何从第二个AsyncTask中止AsyncTask。

这是Log。

04-08 09:22:48.625: E/AndroidRuntime(10950): FATAL EXCEPTION: AsyncTask #3
04-08 09:22:48.625: E/AndroidRuntime(10950): java.lang.RuntimeException: An error occured while executing doInBackground()
04-08 09:22:48.625: E/AndroidRuntime(10950):    at android.os.AsyncTask$3.done(AsyncTask.java:278)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at java.util.concurrent.FutureTask$Sync.innerSetException(FutureTask.java:273)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at java.util.concurrent.FutureTask.setException(FutureTask.java:124)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:307)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at java.util.concurrent.FutureTask.run(FutureTask.java:137)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at android.os.AsyncTask$SerialExecutor$1.run(AsyncTask.java:208)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1076)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:569)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at java.lang.Thread.run(Thread.java:856)
04-08 09:22:48.625: E/AndroidRuntime(10950): Caused by: java.lang.RuntimeException: Can't create handler inside thread that has not called Looper.prepare()
04-08 09:22:48.625: E/AndroidRuntime(10950):    at android.os.Handler.<init>(Handler.java:121)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at android.widget.Toast$TN.<init>(Toast.java:317)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at android.widget.Toast.<init>(Toast.java:91)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at android.widget.Toast.makeText(Toast.java:233)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at tsp.consulting.TransferirDatos$Contador.doInBackground(TransferirDatos.java:184)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at tsp.consulting.TransferirDatos$Contador.doInBackground(TransferirDatos.java:1)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at android.os.AsyncTask$2.call(AsyncTask.java:264)
04-08 09:22:48.625: E/AndroidRuntime(10950):    at java.util.concurrent.FutureTask$Sync.innerRun(FutureTask.java:305)

Answer 1

您的问题是您正在尝试在doInBackground方法中打印Toast。此方法在后台线程中执行，因此无法与UI交互。你可以在这里阅读更多内容。

您可以使用onPostExecute(Result)方法在任务结束后通知用户，或在任务运行时更新onProgressUpdate(Progress...)。

如何从另一个AsyncTask停止（中止）AsyncTask？

1 个答案: