Briefly we can look at the new features introduced in the latest alpha stage in Activity and Fragment which are components of AndroidX.

1. The recent movement in
Activity and Fragment
Wonyoung Choi
@TORU_0239

2. I am…
Wonyoung Choi, a.k.a Toru
Android Advocate,
Singapore Tourism Board
@TORU_0239
Github: TORU239
LinkedIn: linkedin.com/in/toruchoi

3. The latest changes

4. The latest changes
• Noteworthy changes in the latest alpha version
• Activity Results API in activity 1.2.0 alpha
• Fragment Result API in fragment 1.3.0 alpha

5. startActivityForResult()
onActivityResult()
onRequestPermissionsResult()

6. startActivityForResult()
onActivityResult()
onRequestPermissionsResult()
Deprecated on ComponentActivity

7. Activity Results API
• Deprecated method we have been familiar with.
• ActivityResultLauncher and ActivityResultContract
• Resolution for Tight Coupling, Type-Safety, Unwanted NPE

8. implementation 'androidx.activity:activity-ktx:1.2.0-alpha04'

9. import androidx.activity.result.contract.ActivityResultContracts.*
val requestActivity = registerForActivityResult(StartActivityForResult()){ activityResult ->
// Do what you want
}
binding.btn.setOnClickListener {
requestActivity(Intent(...))
}

10. import androidx.activity.result.contract.ActivityResultContracts.*
val requestActivity = registerForActivityResult(StartActivityForResult()){ activityResult ->
// Do what you want
}
binding.btn.setOnClickListener {
requestActivity(Intent(...))
}
ActivityResultLauncher ActivityResultContract

11. Activity Results API
• Available to get result returned like typical Intent
• e.g. Picking Image, Opening Camera using Intent

12. val pickImages = registerForActivityResult(GetContent()){ uri ->
...
}
binding.btnImagePick.setOnClickListener {
pickImages.launch("image/*")
}

13. Activity Results API
• Can handle permission dialog and callback
• Not only single permission but multiple one

14. val permission = registerForActivityResult(RequestPermission()){ enabled ->
// Do what you want
}
binding.btnPermission.setOnClickListener {
permission.launch(android.Manifest.permission.ACCESS_FINE_LOCATION)
}

15. val multiplePermission = registerForActivityResult(RequestMultiplePermissions()) { map ->
// Can do actions we want
}
binding.btnMultipermission.setOnClickListener {
multiplePermission(
arrayOf(
android.Manifest.permission.CAMERA,
android.Manifest.permission.WRITE_EXTERNAL_STORAGE
)
)
}

16. CreateDocument()
GetContent()
GetMultipleContents()
OpenDocument()
OpenDocumentTree()
OpenMultipleDocuments()
PickContact()
RequestMultiplePermissions()
RequestPermission()
StartActivityForResult()
StartIntentSenderForResult()
TakePicture()
TakePicturePreview()
TakeVideo()
Activity Results API

17. Activity Results API
• Customisable ActivityResultContract
• When users need to implement features upon their purpose

18. val customContract = object:ActivityResultContract<String, ActivityResult>(){
override fun createIntent(
context: Context,
input: String?
): Intent {
return Intent(this@CurrentActivity, ResultActivity::class.java).putExtra("test", input)
}
override fun parseResult(
resultCode: Int,
intent: Intent?
): ActivityResult {
return ActivityResult(resultCode, intent)
}
}

19. val customContract = object:ActivityResultContract<String, ActivityResult>(){
override fun createIntent(
context: Context,
input: String?
): Intent {
return Intent(this@CurrentActivity, ResultActivity::class.java).putExtra("test", input)
}
override fun parseResult(
resultCode: Int,
intent: Intent?
): ActivityResult {
return ActivityResult(resultCode, intent)
}
}

20. val customActivity = registerForActivityResult(customContract){ activityResult->
// Can do whatever
}

21. Fragment Results API
• To pass data between Fragments
• No need sharedViewModel or Listener in Activity
• FragmentManager in responsible for working on this

22. Fragment Results API

23. implementation 'androidx.fragment:fragment-ktx:1.3.0-alpha04'

24. setFragmentResult("requestKey", bundleOf("key" to "value"))
fun Fragment.setFragmentResult(
requestKey: String,
result: Bundle?
) = parentFragmentManager.setFragmentResult(requestKey, result)
Sender Fragment

25. setFragmentResultListener("requestKey"){ resultKey, bundle ->
// Do whatever you want
}
fun Fragment.setFragmentResultListener(
requestKey: String,
listener: ((resultKey: String, bundle: Bundle) -> Unit)?
) {
parentFragmentManager.setFragmentResultListener(requestKey, this, listener)
}
Receiver Fragment

26. Fragment Results API

27. setFragmentResult("NESTED_REQUEST_KEY", bundleOf("key" to "value"))
fun Fragment.setFragmentResult(
requestKey: String,
result: Bundle?
) = parentFragmentManager.setFragmentResult(requestKey, result)
Child Fragment

28. childFragmentManager
.setFragmentResultListener(
"NESTED_REQUEST_KEY",
this,
FragmentResultListener { requestKey, result ->
// Whatever you want
}
)
Parent Fragment

29. Further Discussion

30. Limitations
•Still stays at alpha stage
•Possibilities of unexpected changes

31. Further Discussion
•Mechanism of API
•Receiving an activity result in a separate class
•Utilising and combine all the new components

32. Thank You!
Wonyoung Choi
@TORU_0239