CameraSelector

CameraSelector class is used to determine the requirements and priorities to select cameras.

Default CameraSelectors

There are some default CameraSelectors that we can use out-of-the-box:

Default CameraSelector	Description
DEFAULT_BACK_CAMERA	A static CameraSelector that selects the default back facing camera.
DEFAULT_FRONT_CAMERA	A static CameraSelector that selects the default front facing camera.

Here's the equivalent of each constants:

// DEFAULT_BACK_CAMERA
public static final CameraSelector DEFAULT_BACK_CAMERA = new CameraSelector.Builder()
    .requireLensFacing(LENS_FACING_BACK)
    .build();

// DEFAULT_FRONT_CAMERA
public static final CameraSelector DEFAULT_FRONT_CAMERA = new CameraSelector.Builder()
    .requireLensFacing(LENS_FACING_FRONT)
    .build();

Lens Facing Types

As you can see on the above section, CameraSelector class contains some constants that represent the types of camera an app has based on its facing direction. There are 4 of these constants available:

Lens Facing Type
LENS_FACING_FRONT	A camera on the device facing the same direction as the device's screen.
LENS_FACING_BACK	A camera on the device facing the opposite direction as the device's screen.
LENS_FACING_EXTERNAL	An external camera that has no fixed facing relative to the device's screen. The behavior of an external camera highly depends on the manufacturer. Currently it's treated similar to a front facing camera with little verification. So it's considered experimental and should be used with caution.
LENS_FACING_UNKNOWN	A camera on the devices that its lens facing is resolved.

References

• CameraSelector | Android Developers