AsyncTask 完成后主线程崩溃

Question

我正在使用 AsyncTask 从我的服务器获取字符串。

我的问题是，在 AsyncTask 完成后，我的主线程崩溃了，而应用程序是

加载上一个窗口。

奇怪的是，我的 logcat 中没有收到任何错误代码。

感谢您的帮助。

这是我的代码和 logcat：

07-12 00:58:51.162: I/ActivityManager(1834): START u0 {cmp=com.tomer.workoutlog/com.example.workoutlog.AddWorkOutPage (has extras)} from pid 28701
07-12 00:58:51.182: D/AudioHardwareMSM7X30(1489): do_aic3254_control device: 1 mode: 0 record: 0
07-12 00:58:51.182: D/AudioHardwareMSM7X30(1489): aic3254_ioctl: new_aic_rxmode 13 cur_aic_rx 29
07-12 00:58:51.182: D/AudioHardwareMSM7X30(1489): aic3254_ioctl()
07-12 00:58:51.182: D/AudioHardwareMSM7X30(1489): aic3254_ioctl: try ioctl 0x40047313 with arg 13
07-12 00:58:51.192: D/AudioHardwareMSM7X30(1489): aic3254_ioctl: new_aic_txmode 29 cur_aic_tx 29
07-12 00:58:51.192: D/AudioHardwareMSM7X30(1489): value of device and enable is 6 1 ALSA dev id:6
07-12 00:58:51.232: D/AudioHardwareMSM7X30(1489): updateACDB: (11, 6, 0, 607) 
07-12 00:58:51.232: I/HTC Acoustic(1489): update ACDB id: (tx, rx, tx_acdb, rx_acdb) = (11, 6, 0, 607)
07-12 00:58:51.232: D/AudioHardwareMSM7X30(1489): msm_route_stream(PCM_PLAY,5,6,1)
07-12 00:58:51.652: I/ActivityManager(1834): Displayed com.tomer.workoutlog/com.example.workoutlog.AddWorkOutPage: +474ms
07-12 00:58:52.033: W/InputMethodManagerService(1834): Window already focused, ignoring focus gain of: com.android.internal.view.IInputMethodClient$Stub$Proxy@41948370 attribute=null, token = android.os.BinderProxy@415ff880

代码：

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

        /**
         * Before starting background thread Show Progress Dialog
         * */

        @Override
        protected void onPreExecute() {
            super.onPreExecute();
            pDialog = new ProgressDialog(AddWorkOutPage.this);
            pDialog.setMessage("loading...");
            pDialog.setIndeterminate(false);
            pDialog.setCancelable(true);
            pDialog.show();
        }

        /**
         * Creating product
         * */
        protected String doInBackground(String... args) {

                JSONParser jsonParser = new JSONParser();
                JSONObject json = null;
                // Building Parameters
                List<NameValuePair> params = new ArrayList<NameValuePair>();

                params.add(new BasicNameValuePair("exercise", exercise));

                json = jsonParser.makeHttpRequest(url_get_key,"GET", params);

                try {
                    base64EncodedPublicKey = json.getString("key");
                } catch (JSONException e) {
                    // TODO Auto-generated catch block
                    e.printStackTrace();
                }

            // check for success tag
            try {
                int success = json.getInt(TAG_SUCCESS);

                if (success == 1) {
                    // successfully created product

                    //Log.d("ok", json.toString());
                    // closing this screen
                    finish();
                } else {
                    // failed to create product
                }
            } catch (JSONException e) {
                e.printStackTrace();
            }
            return null;
        }

        /**
         * After completing background task Dismiss the progress dialog
         * **/
        protected void onPostExecute(String file_url) {
            pDialog.dismiss();

        }

    }

Answer 1

两个潜在问题：

1. 在我的评论中，您告诉onPostExecute() 接受String，但在doInBackground() 中返回null。我不确定这会导致问题，但我从未尝试过。如果您不想退回任何东西，您可以更改为

   protected void onPostExecute(Void response)

并将您的类声明更改为

 class GetKey extends AsyncTask<String, Void, Void> {

假设您在调用任务时在execute() 中传递了String

2 您在doInBackground() 中调用finish()，但AsyncTask 没有finish() 方法，因此您要么完成Activity，要么在那里出错。

Answer 2

问题是您从 doInBackground() 方法调用 finish()，因此您正在以某种方式修改您的上下文并获得异常。

从结果中返回整数而不是字符串，然后在 onPostExecute() 中完成（）您的活动。

  class GetKey extends AsyncTask<String, String, Integer> {
    /**
     * Before starting background thread Show Progress Dialog
     * */

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        pDialog = new ProgressDialog(AddWorkOutPage.this);
        pDialog.setMessage("loading...");
        pDialog.setIndeterminate(false);
        pDialog.setCancelable(true);
        pDialog.show();
    }

    /**
     * Creating product
     * */
    protected Integer doInBackground(String... args) {
        JSONParser jsonParser = new JSONParser();
        JSONObject json = null;
        // Building Parameters
        List<NameValuePair> params = new ArrayList<NameValuePair>();

        params.add(new BasicNameValuePair("exercise", exercise));

        json = jsonParser.makeHttpRequest(url_get_key,"GET", params);

        try {
            base64EncodedPublicKey = json.getString("key");
        } catch (JSONException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

        // check for success tag
        int success = 0;
        try {
            success = json.getInt(TAG_SUCCESS);                
        } catch (JSONException e) {
            e.printStackTrace();
        }
        return success;
    }

    /**
     * After completing background task Dismiss the progress dialog
     * **/
    protected void onPostExecute(Integer success) {
        pDialog.dismiss();
        if (success == 1) {
           // successfully created product
           //Log.d("ok", json.toString());
           // closing this screen
           finish();
        } else {
           // failed to create product
        }
    }

}