当我试图从一个片段导航到另一个片段时,我遇到了新的Android导航架构组件的问题,我得到了这个奇怪的错误:

java.lang.IllegalArgumentException: navigation destination XXX
is unknown to this NavController

其他导航都很好,除了这个。

我使用Fragment的findNavController()函数来访问NavController。

任何帮助都将不胜感激。


当前回答

在我的案例中,错误发生是因为我在启动画面后启用了带有Single Top和Clear Task选项的导航操作。

其他回答

更新的@Alex坚果解决方案

如果没有特定片段的操作,并希望导航到片段

fun NavController.navigateSafe(
@IdRes actionId: Int, @IdRes fragmentId: Int, args: Bundle? = null,
navOptions: NavOptions? = null, navExtras: Navigator.Extras? = null) 
{
  if (actionId != 0) {
      val action = currentDestination?.getAction(actionId) ?: graph.getAction(actionId)
      if (action != null && currentDestination?.id != action.destinationId) {
          navigate(actionId, args, navOptions, navExtras)
    }
    } else if (fragmentId != 0 && fragmentId != currentDestination?.id)
        navigate(fragmentId, args, navOptions, navExtras)
}

还有另一种解决快速点击导航崩溃问题的方法:

fun NavController.doIfCurrentDestination(@IdRes destination: Int, action: NavController.()-> Unit){
    if(this.currentDestination?.id == destination){action()}
}

然后像这样使用:

findNavController().doIfCurrentDestination(R.id.my_destination){ navigate(...) }

这种解决方案的好处是,您可以轻松地用您已经使用的任何签名包装任何现有的naagte()调用,而不需要进行一百万次重载

为了防止崩溃,我采取了如下措施:

我有一个BaseFragment,在那里我添加了这个乐趣,以确保目的地是已知的currentDestination:

fun navigate(destination: NavDirections) = with(findNavController()) {
    currentDestination?.getAction(destination.actionId)
        ?.let { navigate(destination) }
}

值得注意的是,我正在使用SafeArgs插件。

I caught this exception after some renames of classes. For example: I had classes called FragmentA with @+is/fragment_a in navigation graph and FragmentB with @+id/fragment_b. Then I deleted FragmentA and renamed FragmentB to FragmentA. So after that node of FragmentA still stayed in navigation graph, and android:name of FragmentB's node was renamed path.to.FragmentA. I had two nodes with the same android:name and different android:id, and the action I needed were defined on node of removed class.

您可以在导航之前检查请求导航的Fragment是否仍然是当前目的地,从这个要点出发。

它基本上是在片段上设置一个标记,以便稍后进行查找。

/**
 * Returns true if the navigation controller is still pointing at 'this' fragment, or false if it already navigated away.
 */
fun Fragment.mayNavigate(): Boolean {

    val navController = findNavController()
    val destinationIdInNavController = navController.currentDestination?.id
    val destinationIdOfThisFragment = view?.getTag(R.id.tag_navigation_destination_id) ?: destinationIdInNavController

    // check that the navigation graph is still in 'this' fragment, if not then the app already navigated:
    if (destinationIdInNavController == destinationIdOfThisFragment) {
        view?.setTag(R.id.tag_navigation_destination_id, destinationIdOfThisFragment)
        return true
    } else {
        Log.d("FragmentExtensions", "May not navigate: current destination is not the current fragment.")
        return false
    }
}

R.id。Tag_navigation_destination_id只是一个id,必须添加到ids.xml中,以确保它是唯一的。<item name="tag_navigation_destination_id" type="id" />

更多关于bug和解决方案的信息,以及navigateSafe(…)扩展方法在“修复可怕的”…是未知的NavController”