如果你点击太快，它会导致null和崩溃。

我们可以使用RxBinding库来帮助这一点。你可以在点击发生之前添加节流和持续时间。

 RxView.clicks(view).throttleFirst(duration, TimeUnit.MILLISECONDS)
            .subscribe(__ -> {
            });

这些关于在Android上节流的文章可能会有所帮助。干杯!

看来你在完成任务。应用程序可能有一次性设置或一系列登录屏幕。这些有条件的屏幕不应该被认为是应用程序的起始目的地。

https://developer.android.com/topic/libraries/architecture/navigation/navigation-conditional

在我的情况下，问题发生时，我重用了我的片段内的一个viewpager片段作为viewpager的子。 viewpager片段(父片段)被添加到Navigation xml中，但动作没有添加到viewpager父片段中。

nav.xml
//reused fragment
<fragment
    android:id="@+id/navigation_to"
    android:name="com.package.to_Fragment"
    android:label="To Frag"
    tools:layout="@layout/fragment_to" >
    //issue got fixed when i added this action to the viewpager parent also
    <action android:id="@+id/action_to_to_viewall"
        app:destination="@+id/toViewAll"/>
</fragment>
....
// viewpager parent fragment
<fragment
    android:id="@+id/toViewAll"
    android:name="com.package.ViewAllFragment"
    android:label="to_viewall_fragment"
    tools:layout="@layout/fragment_view_all">

修正了添加动作到父viewpager片段的问题，如下所示:

nav.xml
//reused fragment
<fragment
    android:id="@+id/navigation_to"
    android:name="com.package.to_Fragment"
    android:label="To Frag"
    tools:layout="@layout/fragment_to" >
    //issue got fixed when i added this action to the viewpager parent also
    <action android:id="@+id/action_to_to_viewall"
        app:destination="@+id/toViewAll"/>
</fragment>
....
// viewpager parent fragment
<fragment
    android:id="@+id/toViewAll"
    android:name="com.package.ViewAllFragment"
    android:label="to_viewall_fragment"
    tools:layout="@layout/fragment_view_all"/>
    <action android:id="@+id/action_to_to_viewall"
        app:destination="@+id/toViewAll"/>
</fragment>

似乎混合fragmentManager控件的backstack和Navigation Architecture控件的backstack也会导致这个问题。

例如，最初的CameraX基本示例使用fragmentManager后台导航，如下所示，它似乎没有正确地与导航交互:

// Handle back button press
        view.findViewById<ImageButton>(R.id.back_button).setOnClickListener {
            fragmentManager?.popBackStack()
        }

如果你在从主片段(在本例中是相机片段)移动之前记录这个版本的“当前目的地”，然后当你返回主片段时再次记录它，你可以从日志中的id中看到id是不相同的。据猜测，导航在移动到片段时更新了它，而fragmntManager在移动回来时没有再次更新它。日志显示:

修改前:D/CameraXBasic: currentDest?: androidx.navigation.fragment.FragmentNavigator Destination@b713195美元 After: D/CameraXBasic: currentDest?: androidx.navigation.fragment.FragmentNavigator Destination@9807d8f美元

更新版的CameraX基本示例使用导航返回如下:

 // Handle back button press
        view.findViewById<ImageButton>(R.id.back_button).setOnClickListener {
            Navigation.findNavController(requireActivity(), R.id.fragment_container).navigateUp()
        }

这可以正常工作，当返回到主片段时，日志显示相同的id。

修改前:D/CameraXBasic: currentDest?: androidx.navigation.fragment.FragmentNavigator Destination@b713195美元 After: D/CameraXBasic: currentDest?: androidx.navigation.fragment.FragmentNavigator Destination@b713195美元

我怀疑这个故事的寓意，至少在这个时候，是要非常小心地混合导航和fragmentManager导航。

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.

I am calling the 2.3.1 Navigation and the same error occurs when the application configuration changes. When the cause of the problem was found through Debug, the GaphId in NavHostFragment did not take effect as the ID currently set by calling navController.setGraph(). The GraphId of NavHostFragment can only be obtained from the <androidx.fragment.app.FragmentContainerView/> tag. At this time, this problem will occur if there are multiple GraphIds dynamically set in your code. When the interface is restored, the Destination cannot be found in the cached GraphId. You can solve this problem by manually specifying the value of mGraphId in NavHostFragment through reflection when switching Graph.

navController.setGraph(R.navigation.home_book_navigation);
try {
    Field graphIdField = hostFragment.getClass().getDeclaredField("mGraphId");
    graphIdField.setAccessible(true);
    graphIdField.set(navHostFragment, R.navigation.home_book_navigation);
} catch (NoSuchFieldException | IllegalAccessException e) {
    e.printStackTrace();
}