Android导航错误：java.lang.IllegalArgumentException：导航目标com.example-此NavController未知

Question

[我收到一个错误：java.lang.IllegalArgumentException，仅当我从RegisterFragment导航到LoginFragment，然后按返回按钮转到上一个片段（LoginFragment）并输入电子邮件和密码时，才会发生该错误。按登录按钮。当我在view!!.findNavController().navigate(LoginFragmentDirections.actionLoginFragmentToHomeContainerFragment())行中注释时，不会发生此错误，但我必须导航至HomeFragment。如何解决？

注意：当您不导航到RegisterFragment]时不会发生错误

LoginFragment：

override fun onCreateView(inflater: LayoutInflater, container: ViewGroup?, savedInstanceState: Bundle?): View?
{
    val binding: FragmentLoginBinding = DataBindingUtil.inflate(inflater, R.layout.fragment_login, container, false)

    val login = binding.loginBtn
    val emailField = binding.inputEmail
    val passwordField = binding.inputPassword
    val signUp = binding.loginSignup

    binding.viewModel = viewModel
    binding.lifecycleOwner = this

    signUp.setOnClickListener {
        view!!.findNavController().navigate(LoginFragmentDirections.actionLoginFragmentToRegisterFragment())
    }

    login.setOnClickListener {
        val email = emailField.text.toString().trim()
        val password = passwordField.text.toString().trim()

        if(email.isEmpty())
        {
            .................
        }

        if(!Patterns.EMAIL_ADDRESS.matcher(email).matches())
        {
            .................
        }

        viewModel.userLogin(email,password)
    }

    viewModel.loginAuthData.observe(this, Observer { userAuthData ->
        if(userAuthData.checkAuth != null)
        {
            if(userAuthData.checkAuth!!)
            {
                Snackbar.make(activity!!.findViewById(android.R.id.content), "Auth Pass", Snackbar.LENGTH_SHORT).show()
                //The error doesn't occur if i comment this line >>
                view!!.findNavController().navigate(LoginFragmentDirections.actionLoginFragmentToHomeContainerFragment())
            }
            else
            {
                Snackbar.make(activity!!.findViewById(android.R.id.content), "Auth Fail", Snackbar.LENGTH_SHORT).show()
            }
        }
    })

    return binding.root
}
错误：

  Process: com.example.---, PID: 24721
  java.lang.IllegalArgumentException: navigation destination com.example.---:id/action_loginFragment_to_homeContainerFragment is unknown to this NavController
    at androidx.navigation.NavController.navigate(NavController.java:789)
    at androidx.navigation.NavController.navigate(NavController.java:730)
    at androidx.navigation.NavController.navigate(NavController.java:716)
    at androidx.navigation.NavController.navigate(NavController.java:907)
    at com.example.---.ui.login.LoginFragment$onCreateView$3.onChanged(LoginFragment.kt:71)
    at com.example.---.ui.login.LoginFragment$onCreateView$3.onChanged(LoginFragment.kt:20)
    at androidx.lifecycle.LiveData.considerNotify(LiveData.java:131)
    at androidx.lifecycle.LiveData.dispatchingValue(LiveData.java:149)
    at androidx.lifecycle.LiveData.setValue(LiveData.java:307)
    at androidx.lifecycle.MutableLiveData.setValue(MutableLiveData.java:50)
    at com.example.---.viewModel.LoginViewModel.authCallBack(LoginViewModel.kt:37)
    at com.example.---.viewModel.LoginViewModel.access$authCallBack(LoginViewModel.kt:12)
    at com.example.---.viewModel.LoginViewModel$firebaseUserAuth$1.invoke(LoginViewModel.kt:15)
    at com.example.---.viewModel.LoginViewModel$firebaseUserAuth$1.invoke(LoginViewModel.kt:12)
    at com.example.---.data.FirebaseUserAuth$login$1.onComplete(FirebaseUserAuth.kt:27)
    at com.google.android.gms.tasks.zzj.run(Unknown Source)
    at android.os.Handler.handleCallback(Handler.java:751)
    at android.os.Handler.dispatchMessage(Handler.java:95)
    at android.os.Looper.loop(Looper.java:154)
    at android.app.ActivityThread.main(ActivityThread.java:6077)
    at java.lang.reflect.Method.invoke(Native Method)
    at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:866)
    at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:756)

我收到一个错误：java.lang.IllegalArgumentException，仅当我从LoginFragment导航到RegisterFragment，然后按返回按钮转到上一个片段时，才会发生该错误（...

Answer 1

您正在viewModel.loginAuthData.observe(this, Observer {})中使用onCreateView()，即，使用Fragment（通过this）作为LifecycleOwner进行观察。这始终是错误的-从viewLifecycleOwner进行观察时，您应该改用onCreateView()：

Answer 2