Ch. 17, p. 357: .createIntent() won't accept null argument

[johnpannell]

I’m working through the book, and encountered the following issue. When I attempt to enable/disable the crimeCamera button, I use the code highlighted in the middle of page 357:

val captureImageIntent = takePhoto.contract.createIntent(requireContext(), null)
crimeCamera.isEnabled = canResolveIntent(captureImageIntent)

When run, my program throws an exception:

java.lang.NullPointerException: Parameter specified as non-null is null

… and the trace identifies the first line above as the culprit. I was unable to find the issue debugging, and after commenting out the enable/disable code, I was able to complete the rest of the chapter without a hitch: the camera works, the image is stored, the thumbnail is displayed, etc.

Any advice for a workaround? I’d still like this code to work if it is possible.

[jayssss]

The question was answered here:

Chapter 17: Taking Pictures With Intents - Problem Getting ActivityResult's Intent

No, it looks like you might have found a bug in our code. Your fix works well. Another option people could take is replacing the null with Uri.parse("") so you code looks like: val captureImageIntent = takePhoto.contract.createIntent( requireContext(), Uri.parse(""), ) That particular value isn’t really used by anything. It just needs to be there because the API needs something there in other use cases regarding communicating with other apps. Older versions of libraries allowed nullabl…

[johnpannell]

Fantastic - thanks for your help!

[Columbus]

Since TakePicture() contract requires a Uri for saving pictures it is better to use the next approach:
val canTakePhoto = Intent(MediaStore.ACTION_IMAGE_CAPTURE).resolveActivity(requireContext().packageManager) != null
crimeCamera.isEnabled = canTakePhoto
This code checks whether your device can process an action ACTION_IMAGE_CAPTURE and doesn’t depend on TakePicture limitations.