Q:

Could not take photo with front camera 2

I checkout Camera2Basic (google sample)
and I just changed this method in the class Camera2BasicFragment in order to take a photo with front camera :
  private void setUpCameraOutputs(int width, int height) {
        Activity activity = getActivity();
        CameraManager manager = (CameraManager) activity.getSystemService(Context.CAMERA_SERVICE);
        try {
//            for (String cameraId : manager.getCameraIdList()) {

            mCameraId = "1";
                CameraCharacteristics characteristics
                        = manager.getCameraCharacteristics(mCameraId);

                // We don't use a front facing camera in this sample.
                Integer facing = characteristics.get(CameraCharacteristics.LENS_FACING);
//                if (facing != null && facing == CameraCharacteristics.LENS_FACING_FRONT) {
//                    continue;
//                }

                StreamConfigurationMap map = characteristics.get(
                        CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
//                if (map == null) {
//                    continue;
//                }

                // For still image captures, we use the largest available size.
                Size largest = Collections.max(
                        Arrays.asList(map.getOutputSizes(ImageFormat.JPEG)),
                        new CompareSizesByArea());
                mImageReader = ImageReader.newInstance(largest.getWidth(), largest.getHeight(),
                        ImageFormat.JPEG, /*maxImages*/2);
                mImageReader.setOnImageAvailableListener(
                        mOnImageAvailableListener, mBackgroundHandler);

                // Find out if we need to swap dimension to get the preview size relative to sensor
                // coordinate.
                int displayRotation = activity.getWindowManager().getDefaultDisplay().getRotation();
                //noinspection ConstantConditions
                mSensorOrientation = characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
                boolean swappedDimensions = false;
                switch (displayRotation) {
                    case Surface.ROTATION_0:
                    case Surface.ROTATION_180:
                        if (mSensorOrientation == 90 || mSensorOrientation == 270) {
                            swappedDimensions = true;
                        }
                        break;
                    case Surface.ROTATION_90:
                    case Surface.ROTATION_270:
                        if (mSensorOrientation == 0 || mSensorOrientation == 180) {
                            swappedDimensions = true;
                        }
                        break;
                    default:
                        Log.e(TAG, "Display rotation is invalid: " + displayRotation);
                }

                Point displaySize = new Point();
                activity.getWindowManager().getDefaultDisplay().getSize(displaySize);
                int rotatedPreviewWidth = width;
                int rotatedPreviewHeight = height;
                int maxPreviewWidth = displaySize.x;
                int maxPreviewHeight = displaySize.y;

                if (swappedDimensions) {
                    rotatedPreviewWidth = height;
                    rotatedPreviewHeight = width;
                    maxPreviewWidth = displaySize.y;
                    maxPreviewHeight = displaySize.x;
                }

                if (maxPreviewWidth > MAX_PREVIEW_WIDTH) {
                    maxPreviewWidth = MAX_PREVIEW_WIDTH;
                }

                if (maxPreviewHeight > MAX_PREVIEW_HEIGHT) {
                    maxPreviewHeight = MAX_PREVIEW_HEIGHT;
                }

                // Danger, W.R.! Attempting to use too large a preview size could  exceed the camera
                // bus' bandwidth limitation, resulting in gorgeous previews but the storage of
                // garbage capture data.
                mPreviewSize = chooseOptimalSize(map.getOutputSizes(SurfaceTexture.class),
                        rotatedPreviewWidth, rotatedPreviewHeight, maxPreviewWidth,
                        maxPreviewHeight, largest);

                // We fit the aspect ratio of TextureView to the size of preview we picked.
                int orientation = getResources().getConfiguration().orientation;
                if (orientation == Configuration.ORIENTATION_LANDSCAPE) {
                    mTextureView.setAspectRatio(
                            mPreviewSize.getWidth(), mPreviewSize.getHeight());
                } else {
                    mTextureView.setAspectRatio(
                            mPreviewSize.getHeight(), mPreviewSize.getWidth());
                }

                // Check if the flash is supported.
                Boolean available = characteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE);
                mFlashSupported = available == null ? false : available;

//            }
        } catch (CameraAccessException e) {
            e.printStackTrace();
        } catch (NullPointerException e) {
            // Currently an NPE is thrown when the Camera2API is used but not supported on the
            // device this code runs.
            ErrorDialog.newInstance(getString(R.string.camera_error))
                    .show(getChildFragmentManager(), FRAGMENT_DIALOG);
        }
    }

The front preview is displayed but I could not take photo. 

And each time I trigger the button Picture, this log is displayed : 

11-23 10:08:44.774 15690-16475/com.example.android.camera2basic
  W/LegacyRequestMapper: convertRequestToMetadata - Ignoring
  android.lens.focusDistance false, only 0.0f is supported 11-23
  10:08:44.829 15690-16475/com.example.android.camera2basic
  W/LegacyRequestMapper: convertRequestMetadata - control.awbRegions
  setting is not supported, ignoring value 11-23 10:08:44.832
  15690-16475/com.example.android.camera2basic W/LegacyRequestMapper:
  Only received metering rectangles with weight 0. 11-23 10:08:44.833
  15690-16475/com.example.android.camera2basic W/LegacyMetadataMapper:
  convertAfModeToLegacy - ignoring unsupported mode 4, defaulting to
  fixed

Does anyone has an idea how to fix this problem ? 

A:

To resolve this problem, I declared an attribute mAutoFocusSupported and I initialize in this method : 
private void setUpCameraOutputs(int width, int height) {
       //...
 int[] afAvailableModes = characteristics.get(CameraCharacteristics.CONTROL_AF_AVAILABLE_MODES);
            if (afAvailableModes.length == 0 || (afAvailableModes.length == 1
                    && afAvailableModes[0] == CameraMetadata.CONTROL_AF_MODE_OFF)) {
                mAutoFocusSupported = false;
            } else {
                mAutoFocusSupported = true;
            }

//...
}

and I change the method takePicture like this  : 
  public void takePicture() {
        if (mAutoFocusSupported) {
            lockFocus();
        } else {
            captureStillPicture();
        }
    }

And I changed the callback mCaptureCallback like this : 
   private CameraCaptureSession.CaptureCallback mCaptureCallback
            = new CameraCaptureSession.CaptureCallback() {

        private void process(CaptureResult result) {

            switch (mState) {

                case STATE_PREVIEW: {
                    // We have nothing to do when the camera preview is working normally.
                    break;
                }
                case STATE_WAITING_LOCK: {
                    Integer afState = result.get(CaptureResult.CONTROL_AF_STATE);
                    Log.i(TAG, "STATE_WAITING_LOCK " + mState + " " + afState);

                    if (afState == null) {
                        captureStillPicture();
                    } else if (CaptureResult.CONTROL_AF_STATE_FOCUSED_LOCKED == afState ||
                            CaptureResult.CONTROL_AF_STATE_NOT_FOCUSED_LOCKED == afState ||
                            CaptureResult.CONTROL_AF_STATE_INACTIVE == afState) {
                        // CONTROL_AE_STATE can be null on some devices
                        Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
                        if (aeState == null ||
                                aeState == CaptureResult.CONTROL_AE_STATE_CONVERGED) {
                            mState = STATE_PICTURE_TAKEN;
                            captureStillPicture();
                        } else {
                            runPreCaptureSequence();
                        }
                    }
                    break;
                }
                case STATE_WAITING_PRECAPTURE: {
                    // CONTROL_AE_STATE can be null on some devices
                    Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
                    if (aeState == null ||
                            aeState == CaptureResult.CONTROL_AE_STATE_PRECAPTURE ||
                            aeState == CaptureRequest.CONTROL_AE_STATE_FLASH_REQUIRED) {
                        mState = STATE_WAITING_NON_PRECAPTURE;
                    }
                    break;
                }
                case STATE_WAITING_NON_PRECAPTURE: {
                    // CONTROL_AE_STATE can be null on some devices
                    Integer aeState = result.get(CaptureResult.CONTROL_AE_STATE);
                    if (aeState == null || aeState != CaptureResult.CONTROL_AE_STATE_PRECAPTURE) {
                        mState = STATE_PICTURE_TAKEN;
                        captureStillPicture();
                    }
                    break;
                }
            }
        }

        @Override
        public void onCaptureProgressed(@NonNull CameraCaptureSession session,
                                        @NonNull CaptureRequest request,
                                        @NonNull CaptureResult partialResult) {
//            Log.i(TAG, "onCaptureProgressed " + mState + " "+partialResult);

            process(partialResult);
        }

        @Override
        public void onCaptureCompleted(@NonNull CameraCaptureSession session,
                                       @NonNull CaptureRequest request,
                                       @NonNull TotalCaptureResult result) {
            process(result);
        }

    };

