• Flash-less cameras always return UNAVAILABLE.
• Using CaptureRequest.ControlAeMode== ON_ALWAYS_FLASH will always return FIRED.
• Using CaptureRequest.FlashMode== TORCH will always return FIRED.

Current state of the flash unit.

When the camera device doesn't have flash unit (i.e. CameraCharacteristics.FlashInfoAvailable == false), this state will always be UNAVAILABLE. Other states indicate the current flash status.

In certain conditions, this will be available on LEGACY devices:

In all other conditions the state will not be available on LEGACY devices (i.e. it will be null).

Possible values:

• CameraMetadata.FLASH_STATE_UNAVAILABLE
• CameraMetadata.FLASH_STATE_CHARGING
• CameraMetadata.FLASH_STATE_READY
• CameraMetadata.FLASH_STATE_FIRED
• CameraMetadata.FLASH_STATE_PARTIAL

Optional - This value may be null on some devices.

Limited capability - Present on all camera devices that report being at least CameraMetadata.INFO_SUPPORTED_HARDWARE_LEVEL_LIMITED devices in the CameraCharacteristics.InfoSupportedHardwareLevel key

[Android Documentation]