MakePaymentScreen.kt

/* Copyright 2022 Google LLC.	
   SPDX-License-Identifier: Apache-2.0 */

//////////////////////////////////////////////
// Jetpack Compose code
//////////////////////////////////////////////

@Composable
fun MakePaymentScreen(
    onPaymentMade: (Boolean) -> Unit,
    viewModel: MakePaymentViewModel = viewModel()
) {
    val currentOnPaymentMade by rememberUpdatedState(onPaymentMade)
    val lifecycle = LocalLifecycleOwner.current.lifecycle

    // Check whenever navigateToPaymentResultScreen emits a new value
    // to tell the caller composable the payment was made
    LaunchedEffect(viewModel, lifecycle)  {
        lifecycle.repeatOnLifecycle(state = STARTED) {
            viewModel.navigateToPaymentResultScreen.collect { isPaymentSuccessful ->
                currentOnPaymentMade(isPaymentSuccessful)
            }
        }
    }

    // Rest of the UI for the make payment screen.
}


//////////////////////////////////////////////
// Activity / Views code
//////////////////////////////////////////////

class MakePaymentActivity : AppCompatActivity() {
    private val viewModel: MakePaymentViewModel by viewModels()

    override fun onCreate(savedInstanceState: Bundle?) {
        /* ... */
        lifecycleScope.launch {
            repeatOnLifecycle(Lifecycle.State.STARTED) {
                viewModel.navigateToPaymentResultScreen.collect { isPaymentSuccessful ->
                    val intent = Intent(this, PaymentResultActivity::class.java)
                    intent.putExtra("PAYMENT_RESULT", isPaymentSuccessful)
                    startActivity(intent)
                    finish()
                }
            }
        }
    }
}