findNavController().navigate() get invokeSuspend and Fragment$InstantiationException calling Fragmen-CodePudding

logcat error: invoke suspend at findNavController().navigate(navDirections)

viewLifecycleOwner.lifecycleScope.launch {
            viewLifecycleOwner.repeatOnLifecycle(Lifecycle.State.STARTED) {
                viewModel.goodInfoStateFlow.collectLatest { goodInfoState ->
                    when (goodInfoState) {
                        is GoodInfoState.Success -> {

                            val goodInfo = goodInfoState.goodInfo

                            Log.d(TAG, "goodInfo: $goodInfo")

                                val navDirections =
                            CargoFragmentDirections.actionCargoFragmentToGoodInfoJourneysFragment(
                                goodInfo
                            )
                        findNavController().navigate(navDirections)

                        }
                        is GoodInfoState.Error -> {
                            AlertDialog.Builder(requireContext())
                                .setMessage(goodInfoState.message)
                                .setNegativeButton(
                                    "Cancel"
                                ) { dialogInterface, _ ->
                                    dialogInterface.dismiss()
                                }
                        }
//                        GoodInfoState.Loading -> TODO()
                    }
                }
            }
        }

Error Message: androidx.fragment.app.Fragment$InstantiationException: Unable to instantiate fragment .GoodInfoJourneysFragment: calling Fragment constructor caused an exception at androidx.fragment.app.Fragment.instantiate(Fragment.java:633) at androidx.fragment.app.FragmentContainer.instantiate(FragmentContainer.java:57) at androidx.fragment.app.FragmentManager$2.instantiate(FragmentManager.java:448) at androidx.navigation.fragment.FragmentNavigator.instantiateFragment(FragmentNavigator.java:132) at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.java:162) at androidx.navigation.fragment.FragmentNavigator.navigate(FragmentNavigator.java:58) at androidx.navigation.NavController.navigate(NavController.java:1066) at androidx.navigation.NavController.navigate(NavController.java:944) at androidx.navigation.NavController.navigate(NavController.java:877) at androidx.navigation.NavController.navigate(NavController.java:863) at androidx.navigation.NavController.navigate(NavController.java:851) at $onViewCreated$1$1$1.invokeSuspend(CargoFragment.kt:97)

java.lang.NullPointerException at fragment.GoodInfoJourneysFragment.(GoodInfoJourneysFragment.kt:17)

CodePudding user response：

After I change to -> private val binding get() =

And solved this problem.

Origin:

class CargoFragment : Fragment() {

    private var _binding: FragmentCargoBinding? = null
    private val binding = _binding!!
}

After modify:

class CargoFragment : Fragment() {

    private var _binding: FragmentCargoBinding? = null
    private val binding get() = _binding!!
}

CodePudding user response：

Kindly check your GoodInfoJourneysFragment's code on line 17. The line in the exception stack trace

java.lang.NullPointerException at fragment.GoodInfoJourneysFragment.(GoodInfoJourneysFragment.kt:17)

says that you have some object that you try to use, but it hasn't been instantiated before using.