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

在思考了Ian Lake在推特上的建议后,我想出了以下方法。将NavControllerWrapper定义如下:

class NavControllerWrapper constructor(
  private val navController: NavController
) {

  fun navigate(
    @IdRes from: Int,
    @IdRes to: Int
  ) = navigate(
    from = from,
    to = to,
    bundle = null
  )

  fun navigate(
    @IdRes from: Int,
    @IdRes to: Int,
    bundle: Bundle?
  ) = navigate(
    from = from,
    to = to,
    bundle = bundle,
    navOptions = null,
    navigatorExtras = null
  )

  fun navigate(
    @IdRes from: Int,
    @IdRes to: Int,
    bundle: Bundle?,
    navOptions: NavOptions?,
    navigatorExtras: Navigator.Extras?
  ) {
    if (navController.currentDestination?.id == from) {
      navController.navigate(
        to,
        bundle,
        navOptions,
        navigatorExtras
      )
    }
  }

  fun navigate(
    @IdRes from: Int,
    directions: NavDirections
  ) {
    if (navController.currentDestination?.id == from) {
      navController.navigate(directions)
    }
  }

  fun navigateUp() = navController.navigateUp()

  fun popBackStack() = navController.popBackStack()
}

然后在导航代码中:

val navController = navControllerProvider.getNavController()
navController.navigate(from = R.id.main, to = R.id.action_to_detail)

其他回答

在思考了Ian Lake在推特上的建议后,我想出了以下方法。将NavControllerWrapper定义如下:

class NavControllerWrapper constructor(
  private val navController: NavController
) {

  fun navigate(
    @IdRes from: Int,
    @IdRes to: Int
  ) = navigate(
    from = from,
    to = to,
    bundle = null
  )

  fun navigate(
    @IdRes from: Int,
    @IdRes to: Int,
    bundle: Bundle?
  ) = navigate(
    from = from,
    to = to,
    bundle = bundle,
    navOptions = null,
    navigatorExtras = null
  )

  fun navigate(
    @IdRes from: Int,
    @IdRes to: Int,
    bundle: Bundle?,
    navOptions: NavOptions?,
    navigatorExtras: Navigator.Extras?
  ) {
    if (navController.currentDestination?.id == from) {
      navController.navigate(
        to,
        bundle,
        navOptions,
        navigatorExtras
      )
    }
  }

  fun navigate(
    @IdRes from: Int,
    directions: NavDirections
  ) {
    if (navController.currentDestination?.id == from) {
      navController.navigate(directions)
    }
  }

  fun navigateUp() = navController.navigateUp()

  fun popBackStack() = navController.popBackStack()
}

然后在导航代码中:

val navController = navControllerProvider.getNavController()
navController.navigate(from = R.id.main, to = R.id.action_to_detail)

我写了这个扩展

fun Fragment.navigateAction(action: NavDirections) {
    val navController = this.findNavController()
    if (navController.currentDestination?.getAction(action.actionId) == null) {
        return
    } else {
        navController.navigate(action)
    }
}

在我的情况下,我通过验证所有导航操作都正确地管理到各自的图形中,并更新了设备后退按钮的代码来解决这个问题,如下所示:

 onBackPressedDispatcher.addCallback(this /* lifecycle owner */, object : OnBackPressedCallback(true) {
        override fun handleOnBackPressed() {
            // Back is pressed... Finishing the activity
            if (navHostFragment.childFragmentManager.backStackEntryCount == 0) {
                // First fragment is open, backstack is empty
               finish()
            } else {
                navHostFragment.navController.popBackStack()
            }
        }
    })

在我的例子中,如果用户非常非常快地点击同一个视图两次,这个崩溃就会发生。所以你需要实现某种逻辑来防止多次快速点击……这很烦人,但似乎是必要的。

你可以在这里阅读更多关于防止这种情况的内容:Android防止双击按钮

编辑3/19/2019:为了进一步澄清一点,这个崩溃不是仅仅通过“非常非常快地单击同一个视图两次”就可以完全重现的。或者,您可以使用两个手指同时单击两个(或更多)视图,其中每个视图都有自己的导航。当你有一个项目列表时,这尤其容易做到。以上关于多次点击预防的信息将处理这种情况。

编辑4/16/2020:以防你对上面的Stack Overflow帖子不太感兴趣,我包括了我自己的(Kotlin)解决方案,我已经使用了很长一段时间了。

OnSingleClickListener.kt

class OnSingleClickListener : View.OnClickListener {

    private val onClickListener: View.OnClickListener

    constructor(listener: View.OnClickListener) {
        onClickListener = listener
    }

    constructor(listener: (View) -> Unit) {
        onClickListener = View.OnClickListener { listener.invoke(it) }
    }

    override fun onClick(v: View) {
        val currentTimeMillis = System.currentTimeMillis()

        if (currentTimeMillis >= previousClickTimeMillis + DELAY_MILLIS) {
            previousClickTimeMillis = currentTimeMillis
            onClickListener.onClick(v)
        }
    }

    companion object {
        // Tweak this value as you see fit. In my personal testing this
        // seems to be good, but you may want to try on some different
        // devices and make sure you can't produce any crashes.
        private const val DELAY_MILLIS = 200L

        private var previousClickTimeMillis = 0L
    }

}

ViewExt.kt

fun View.setOnSingleClickListener(l: View.OnClickListener) {
    setOnClickListener(OnSingleClickListener(l))
}

fun View.setOnSingleClickListener(l: (View) -> Unit) {
    setOnClickListener(OnSingleClickListener(l))
}

HomeFragment.kt

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
    super.onViewCreated(view, savedInstanceState)

    settingsButton.setOnSingleClickListener {
        // navigation call here
    }
}

在调用navigate之前检查currentDestination可能会有帮助。

例如,如果您在导航图fragmentA和fragmentB上有两个片段目的地,并且从fragmentA到fragmentB只有一个动作。当你已经在fragmentB上时,调用navigate(R.id.action_fragmentA_to_fragmentB)将导致IllegalArgumentException。因此,在导航之前,你应该总是检查currentDestination。

if (navController.currentDestination?.id == R.id.fragmentA) {
    navController.navigate(R.id.action_fragmentA_to_fragmentB)
}