AndroidX 导航 navigateUp 两次

Question

I am using the new AndroidX navigation framework.

I have a few fragments all linked in a navigation chain.

FragmentA --> FragmentB --> FragmentC

FragmentC has a Cancel button that should send me up all the way back to FragmentA.

Should I do the following:
on FragmentC call the method:

 Navigation.findNavController(view).navigateUp();

then on FragmentB listen to some callback and using some passed parameter or argument trigger another navigateUp() function from FragmentB

or is there some method that will do the equivalent of navigateUpTwice()

Answer 1

我最终做的是

Navigation.findNavController(view).popBackStack(R.id.fragmant_a,false)

Answer 2

In your navigation.xml file under the action that you have created to navigate to starting fragment (FragmentA in your case) add the following

<action
....
app:popUpTo="@id/fragmentA"
app:popUpToInclusive="false"/>

This will pop up all the fragments until FragmentA and will exclude FragmentA since popUpToInclusive is set to false .

Edit: The full form of your action under FragmentC tag of your navigation.xml file will be something similar to this:

<fragment
    android:id="@+id/FragmentC"
    android:name="com.yourdomain.FragmentC"
    android:label="FragmentC">
    <action
        android:id="@+id/action_fragmentC_to_fragmentA"
        app:destination="@id/fragmentA"
        app:popUpTo="@id/fragmentA"
        app:popUpToInclusive="false"/>
</fragment>

Answer 3

您可以从 FragmentB --> FragmentC 在您的操作中将 pop 设置为 FragmentA，然后当您按回时它会转到 Fragment A 而不是 Fragment B

Answer 4

Try with this, it works for me.

findNavController().navigateUp()
findNavController().navigateUp()

Answer 5

So I found myself in a situation where I had to navigateUp() twice, but with a twist: I could reach the view through several paths. Think of it like this:

Fragment A --> Fragment C --> Fragment D

Fragment B --> Fragment C --> Fragment D

In a normal situation, using the popTo xml attribute or the popBackStack() method would work. However it is unusable here. Fortunately, what you can do is:

val navController = NavHostFragment.findNavController(this)
navController.navigateUp()
navController.navigateUp

As other people have pointed out, this is absolutely not optimised performance-wise. In any situation where you can reach Fragment D through a single path, use popTo instead.