How to replace startActivityForResult with Activity Result APIs?

Question

I have a main activity which serves as an entry point to call different activities, depending on condition. Among others, I use Firebase Auth to manage user sign in:

startActivityForResult(
            AuthUI.getInstance().createSignInIntentBuilder()
                    .setAvailableProviders(providers)
                    .build(),
            RC_SIGN_IN)

I overwrite onActivityResult() to distinguish the returned intent/data, for example:

 override fun onActivityResult(requestCode: Int, resultCode: Int, data: Intent?) {
    super.onActivityResult(requestCode, resultCode, data)
    when (requestCode) {

        REQUEST_CODE_1 -> {
          // update UI and stuff
        }

        RC_SIGN_IN -> {
          // check Firebase log in
        }
        // ...
    }
}

With the Activity Result APIs which is strongly recommended by the documentation, I get that I should make prepareCall() before ActivityResultLauncher and to make sure the activity is in created state when I launch, but I still don't understand how to handle multiple activity results gracefully (at least, in one place) like in onActivityResult().

Looking at this article, it seems I need to implement multiple child inner classes of ActivityResultContract type (therefore multiple prepareCall()'s?), because they are suppose to be different contracts, am I correct? Can someone please show me some skeleton example that mirrors the above onActivityResult() logic?

Answer 1

You can call as many Activities for result as you wish and have separate callback for each:

    val startForResult = registerForActivityResult(ActivityResultContracts.StartActivityForResult())
    { result: ActivityResult ->
        if (result.resultCode == Activity.RESULT_OK) {
            //  you will get result here in result.data
            }

        }
    }

    startForResult.launch(Intent(activity, CameraCaptureActivity::class.java))

You just need to specify Activity class - CameraCaptureActivity::class.java

Update:

The prepareCall() method has been renamed to registerForActivityResult() in Activity 1.2.0-alpha04 and Fragment 1.3.0-alpha04. And it should be startForResult.launch(...) in the last line

Thanks Rafael Tavares for update

Answer 2

From now, startActivityForResult() has been deprecated so use new method instead of that.

Example

public void openActivityForResult() {
    
 //Instead of startActivityForResult use this one
        Intent intent = new Intent(this,OtherActivity.class);
        someActivityResultLauncher.launch(intent);
    }


//Instead of onActivityResult() method use this one

    ActivityResultLauncher<Intent> someActivityResultLauncher = registerForActivityResult(
            new ActivityResultContracts.StartActivityForResult(),
            new ActivityResultCallback<ActivityResult>() {
                @Override
                public void onActivityResult(ActivityResult result) {
                    if (result.getResultCode() == Activity.RESULT_OK) {
                        // Here, no request code
                        Intent data = result.getData();
                        doSomeOperations();
                    }
                }
            });

Answer 3

First, don’t forget to add this to your Gradle dependency

implementation 'androidx.activity:activity-ktx:1.2.0-alpha05'
implementation 'androidx.fragment:fragment-ktx:1.3.0-alpha05'

Second, create your result contract by extending an abstract class called ActivityResultContract<I, O>. I mean the type of input and O means the type of output. And then you only need to override 2 methods

class PostActivityContract : ActivityResultContract<Int, String?>() {

    override fun createIntent(context: Context, input: Int): Intent {
        return Intent(context, PostActivity::class.java).apply {
            putExtra(PostActivity.ID, postId)
        }
    }

    override fun parseResult(resultCode: Int, intent: Intent?): String? {
        val data = intent?.getStringExtra(PostActivity.TITLE)
        return if (resultCode == Activity.RESULT_OK && data != null) data
        else null
    }
}

And finally, the last step is registering the contract to Activity. You need to pass your custom contract and callback into registerForActivityResult.

class MainActivity : AppCompatActivity() {

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
      
        start_activity_contract.setOnClickListener {
            openPostActivityCustom.launch(1)
        }
    }
  
    // Custom activity result contract
    private val openPostActivityCustom =
        registerForActivityResult(PostActivityContract()) { result ->
            // parseResult will return this as string?                                              
            if (result != null) toast("Result : $result")
            else toast("No Result")
        }
}

For More info check this Post

Answer 4

In this case, what was returned by AuthUI was already an Intent, so, we use it like in the example below.

private val startForResult =
        registerForActivityResult(ActivityResultContracts.StartActivityForResult()) { result ->
            when(result.resultCode){
                RESULT_OK -> {
                    val intent = result.data
                    // Handle the Intent...
                    mUser = FirebaseAuth.getInstance().currentUser
                }
                RESULT_CANCELED -> {

                } else -> {
            } }
        }

start the activity from anywhere (for example on button click) using:

 AuthUI.getInstance().createSignInIntentBuilder().setAvailableProviders(providers)
            .build().apply {
                startForResult.launch(this)
            }