Question

我在AsyncTask类中获得了设备的GPS协调（通过getLocation方法）但是，如果GPS被禁用，我打开一个对话框，用户可以转移到＆＃34;设置＆＃34;区域并转动GPS＆＃34; on＆＃34;或取消。每次打开对话框警报之前应用程序崩溃，然后用户甚至按下其中一个按钮。我该如何解决？

    public class StarTask extends AsyncTask<Void,Void,ArrayList<Song>>{

    final int k_ThreadSleepTime = 3000;
    final int k_MaxThreadTries = 7;
    double latitude = 0;
    double longitude = 0;
    GPSTracker gps;
    TestMain client;

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
        gps = new GPSTracker(getApplication());
    }

    @Override
    protected ArrayList<Song> doInBackground(Void... params) {
        ArrayList<Song> list = new ArrayList();
        client = new TestMain();
        int tries = 0;
        String o;
        getLocation();
        String url = builtURL();
        try {
            String jsonPageStr = client.doGetRequest(url);
            JSONObject obj = new JSONObject(jsonPageStr);
            userId = obj.getJSONObject("info").getInt("user_id");
            isWait = (wait.equals("true"));

            while (isWait && tries < k_MaxThreadTries) {
                url = builtURL();
                jsonPageStr = client.doGetRequest(url);
                obj = new JSONObject(jsonPageStr);
                if (!(obj.equals("") || obj.equals(null))) {
                    isWait = (wait.equals("true"));
                }
                tries++;
                try {
                    Thread.sleep(k_ThreadSleepTime);
                } catch (InterruptedException e) {
                    e.printStackTrace();
                }
            }

            if(tries == k_MaxThreadTries) {
                //exit the App
                onMyDestroy();
            }
    }

    private String builtURL() {}

    private void getLocation() {
        if (gps.canGetLocation()) {
            latitude = gps.getLatitude();
            longitude = gps.getLongitude();

        } else {
            // can't get location
            // GPS or Network is not enabled
            // Ask user to enable GPS/network in settings

            //gps.showSettingsAlert();

            showSettingsAlert();
        }
        gps.stopUsingGPS();
    }

    public void showSettingsAlert(){

        runOnUiThread(new Runnable() {
            @Override
            public void run() {
                final AlertDialog.Builder alertDialog = new AlertDialog.Builder(MainActivity.this);

                // Setting Dialog Title
                alertDialog.setTitle("GPS is settings");

                // Setting Dialog Message
                alertDialog.setMessage("GPS is not enabled. Do you want to go to settings menu?");

                // On pressing Settings button
                alertDialog.setPositiveButton("Settings", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog,int which) {
                        Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                        MainActivity.this.startActivity(intent);
                        hasBeenNoGps = true;
                    }
                });

                // on pressing cancel button
                alertDialog.setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                    public void onClick(DialogInterface dialog, int which) {
                        dialog.cancel();
                        hasBeenNoGps = true;
                        onMyDestroy();
                    }
                });

                // Showing Alert Message
                alertDialog.show();
            }
        });
    }

    @Override
    protected void onPostExecute(ArrayList<Song> aVoid) {
        super.onPostExecute(aVoid);

Answer 1

您正在showSettingsAlert()上执行用户操作，该操作在doInBackground()的{{1}}期间调用。允许的方法是使涉及UI的所有操作远离AsyncTask。在这里，您可以从doInBackground()中移除else条件，而不是实现它getLocation()。像这样，

onPreExecute()

Answer 2

您正在尝试在后台线程（在AsyncTask内）中运行UI线程，您可以做的是在AsyncTask类中创建一个全局对话框并在 doInBackground 方法上显示它然后关闭它 onPostExecute（）。您的对话框需要上下文。

Android App崩溃与对话框

2 个答案: