如果 activity 停止并再次启动，请求启用 GPS 发生两次

Question

我有一个 activity，它要求用户通过显示带有“确定”和“取消”按钮的对话框在 onStart() 中启用 GPS。但是，如果用户在与对话框交互之前按下主页按钮，然后再次启动应用程序，则会在旧对话框之上出现一个新对话框，因此用户会一个接一个地看到两个对话框。如何关闭 activity?

的 onStop 方法中的旧对话框

这是我的代码的相关部分：

protected void onStart() {
    super.onStart();
    enableGPS();
}

private void enableGPS() {                                      //GPS ENABLE RELATED METHOD
    LocationSettingsRequest.Builder builder = new LocationSettingsRequest.Builder()
            .addLocationRequest(mLocationRequest);
    builder.setAlwaysShow(true);

    PendingResult<LocationSettingsResult> result = LocationServices.SettingsApi
            .checkLocationSettings(mGoogleApiClient, builder.build());
    result.setResultCallback(new ResultCallback<LocationSettingsResult>() {
        @Override
        public void onResult(LocationSettingsResult result) {
            final Status status = result.getStatus();
            final LocationSettingsStates state = result
                    .getLocationSettingsStates();
            switch (status.getStatusCode()) {
                case LocationSettingsStatusCodes.SUCCESS:                           //GPS ALREDY TURNED ON
                    if (locationServiceConnected) {
                        if (ActivityCompat.checkSelfPermission(enableGPSActivity.this, android.Manifest.permission.ACCESS_FINE_LOCATION)== PackageManager.PERMISSION_GRANTED) {
                            LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, enableGPSActivity.this);
                        }
                    }
                    else {
                        redirectStatus.setText("ERROR: Not able to connect to Location Service");
                        btnRetry.setVisibility(View.VISIBLE);
                    }
                    break;
                case LocationSettingsStatusCodes.RESOLUTION_REQUIRED:               //GPS NOT ALREDY TURNED ON, SHOW TURN ON DIALOG
                    try {
                        status.startResolutionForResult(enableGPSActivity.this, REQUEST_CHECK_SETTINGS); //CREATING DIALOG FOR GPS TURN ON
                    } catch (IntentSender.SendIntentException e) {
                    }
                    break;
                case LocationSettingsStatusCodes.SETTINGS_CHANGE_UNAVAILABLE:       //GPS CANNOT BE TURNED ON
                    redirectStatus.setText("Permission Available, not able to enable GPS");
                    btnRetry.setVisibility(View.VISIBLE);
                    break;
            }
        }
    });
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {             //GPS ENABLE RELATED METHOD, DIALOG FOR GPS TURN ON
    if (requestCode == REQUEST_CHECK_SETTINGS) {
        if (resultCode == Activity.RESULT_OK) {                 // GPS TURN ON ACCEPTED
            if (locationServiceConnected) {
                if (ActivityCompat.checkSelfPermission(enableGPSActivity.this, android.Manifest.permission.ACCESS_FINE_LOCATION)== PackageManager.PERMISSION_GRANTED) {
                    redirectStatus.setText("Please Wait. Fetching Your Current Location");
                    LocationServices.FusedLocationApi.requestLocationUpdates(mGoogleApiClient, mLocationRequest, enableGPSActivity.this);
                }
            }
        }
        if (resultCode == Activity.RESULT_CANCELED) {               //GPS TURN ON REJECTED
            redirectStatus.setText("Permission Available, GPS Off");
            btnRetry.setVisibility(View.VISIBLE);
        }
    }
}

}

Answer 1

  //  declares variables name 

        private AlertDialog gpsAlertDialog;
        private boolean  isGpsDialogShowing = false;
        private LocationManager manager;


      // check gps enable or not if enable than remove dialog else show gps enable dialog in onResume method


protected void onResume() 
        {          
    if (!manager.isProviderEnabled(LocationManager.GPS_PROVIDER)&&!manager.isProviderEnabled(LocationManager.NETWORK_PROVIDER)) {
                    ShowGpsDialog();
                } else {
                    removeGpsDialog();
                }


            }


 //   remove dialog on destroy activity 

    @Override
        protected void onDestroy() {
            super.onDestroy();
            removeGpsDialog();
        }


 //   method for show dialog for gps enable    


          private void ShowGpsDialog() {

                isGpsDialogShowing = true;
                AlertDialog.Builder gpsBuilder = new AlertDialog.Builder(
                        MainMenuDrawerActivity.this);
                gpsBuilder.setCancelable(false);
                gpsBuilder
                        .setTitle(getString(R.string.dialog_no_gps))
                        .setMessage(getString(R.string.dialog_no_gps_messgae))
                        .setPositiveButton(getString(R.string.dialog_enable_gps),
                                new DialogInterface.OnClickListener() {
                                    public void onClick(DialogInterface dialog,
                                                        int which) {
                                        // continue with delete
                                        Intent intent = new Intent(Settings.ACTION_LOCATION_SOURCE_SETTINGS);
                                        startActivity(intent);
                                        removeGpsDialog();
                                    }
                                })

                        .setNegativeButton(getString(R.string.dialog_exit),
                                new DialogInterface.OnClickListener() {
                                    public void onClick(DialogInterface dialog,
                                                        int which) {
                                        // do nothing
                                        removeGpsDialog();
                                        finish();
                                    }
                                });
                gpsAlertDialog = gpsBuilder.create();
                gpsAlertDialog.show();
            }



      //  method for remove gps dialog 


            private void removeGpsDialog() {
                if (gpsAlertDialog != null && gpsAlertDialog.isShowing()) {
                    gpsAlertDialog.dismiss();
                    isGpsDialogShowing = false;
                    gpsAlertDialog = null;

                }
            }

Answer 2

将 enableGPS(); 调用到 onCreate() 而不是 onStart()。
因为，

根据Activity的生命周期 - 当用户按下主页按钮时，当前activity将进入后台通过调用 - onPause() 和 onStop() 方法 。 当您从 Stack 恢复 activity 时 - Activity 将通过调用 onRestart()、onStart() 和 恢复=19=].

如果 activity 停止并再次启动，请求启用 GPS 发生两次

Request to enable GPS occuring twice if activity stopped and started again

gps

android