How does one retrieve the cameraID and use setTorchMode?

Question

So Android M recently came out and it now has a built in cameralight function called setTorchMode. I was curious as to how this worked as the parameters are (String cameraID, Bo

Answer 1

 if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
        mCameraManager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE);
        try {
            for (String camID : mCameraManager.getCameraIdList()) {
                CameraCharacteristics cameraCharacteristics = mCameraManager.getCameraCharacteristics(camID);
                int lensFacing = cameraCharacteristics.get(CameraCharacteristics.LENS_FACING);
                if (lensFacing == CameraCharacteristics.LENS_FACING_FRONT && cameraCharacteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE)) {
                    mCameraId = camID;
                    break;
                } else if (lensFacing == CameraCharacteristics.LENS_FACING_BACK && cameraCharacteristics.get(CameraCharacteristics.FLASH_INFO_AVAILABLE)) {
                    mCameraId = camID;
                }
            }
            if (mCameraId != null) {
                mCameraManager.setTorchMode(mCameraId, true);
            }
        } catch (CameraAccessException e) {
            e.printStackTrace();
        }
    }

mCameraId will turn on front camera flash if available or else back camera flash if available. If no flash is available then mCameraId will be null and setTorchMode will not be called.