If using the emulator for development, you will need to configure it to have a camera. If the computer you are using has a webcam, the emulator can use it as the camera; otherwise, you can choose to have an emulated camera.
To configure the emulator for a camera, perform the following steps:
From the main menu navigate to Tools | Open Android Emulator Manager.
Select the emulator you have been working with and choose Edit.
In the middle of the Edit AVD dialog, you will see two dropdowns; one for Front Camera and one for Back Camera. Make your selections and click on OK.