android - 旋转时导航组件崩溃

Question

设备旋转时导航组件崩溃

2019-04-15 11:50:08.589 21493-21493/me.rankov.kaboom E/AndroidRuntime: FATAL EXCEPTION: main
    Process: me.rankov.kaboom, PID: 21493
    java.lang.IllegalArgumentException: navigation destination me.rankov.kaboom:id/actionHomeToCountry is unknown to this NavController
        at androidx.navigation.NavController.navigate(NavController.java:803)
        at androidx.navigation.NavController.navigate(NavController.java:744)
        at androidx.navigation.NavController.navigate(NavController.java:730)
        at androidx.navigation.NavController.navigate(NavController.java:718)
        at me.rankov.kaboom.login.LoginActivity.navigateToRegister(LoginActivity.kt:22)
        at me.rankov.kaboom.login.LoginPresenterImpl.checkRegistration(LoginPresenterImpl.kt:49)
        at me.rankov.kaboom.login.LoginPresenterImpl.onStart(LoginPresenterImpl.kt:37)
        at me.rankov.kaboom.login.LoginActivity.onStart(LoginActivity.kt:45)
        at android.app.Instrumentation.callActivityOnStart(Instrumentation.java:1392)
        at android.app.Activity.performStart(Activity.java:7231)

这里崩溃了

override fun navigateToRegister(fragmentId: Int, bundle: Bundle) {
    findNavController(R.id.login_host_fragment).navigate(fragmentId, bundle)
}

我通过 onStart 事件从演示者调用它

val nickname = loginInteractor.getNickname()
val country = loginInteractor.getCountry()
when {
    nickname.isEmpty() -> {
        val bundle = bundleOf("user" to user)
        loginView?.navigateToRegister(R.id.actionHomeToName, bundle)
    }
    country < 0 -> loginView?.navigateToRegister(R.id.actionHomeToCountry)
    else -> loginView?.navigateToMain()
}

完整代码在这里:login activity和 presenter

这是我的主机 fragment :

<fragment
    android:id="@+id/login_host_fragment"
    android:name="androidx.navigation.fragment.NavHostFragment"
    android:layout_width="395dp"
    android:layout_height="322dp"
    android:layout_marginStart="8dp"
    android:layout_marginTop="8dp"
    android:layout_marginEnd="8dp"
    android:layout_marginBottom="8dp"
    app:defaultNavHost="true"
    app:layout_constraintBottom_toBottomOf="parent"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toStartOf="parent"
    app:layout_constraintTop_toTopOf="parent"
    app:navGraph="@navigation/login" />

这是navigation graph .

无需改变方向，它就能按预期工作。

Answer 1

更改配置后导航 Controller 后退堆栈出现问题

在带有 fragment 的 Activity 中:在更改配置之前尝试保存导航 Controller 状态。更改配置后，再次将其添加回导航 Controller 。喜欢:

override fun onSaveInstanceState(savedInstanceState: Bundle) {
    super.onSaveInstanceState(savedInstanceState)
    savedInstanceState.putBundle("nav_state", fragment.findNavController().saveState())
}
override fun onRestoreInstanceState(savedInstanceState: Bundle) {
    super.onRestoreInstanceState(savedInstanceState)
    fragment.findNavController().restoreState(savedInstanceState.getBundle("nav_state"))
}

这就是我的情况