I have an activity and used a navgraph to navigate through three fragments. This goes from Fragment1 to Fragment2 to Fragment3 and it works.
However, from Fragment3 I start a new activity. In this activity, I want to display either of two fragments within its FragmentContainerView. Let's call one FragmentList and one FragmentEmpty.
I have created a navgraph for this:
<navigation xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/nav"
app:startDestination="@id/empty_fragment">
<fragment
android:id="@+id/empty_fragment"
android:name="com.project.EmptyFragment"
android:label="EmptyFragment" />
<fragment
android:id="@+id/list_fragment"
android:name="com.project.ListFragment"
android:label="ListFragment" />
</navigation>
I get that the startDestination basically works like a "default" here when I really want to display either one of two as the real start destination. So in the case where I want list_fragment this would be unnecessarily set and then overwritten. But it's a required field, so I have to set it.
To start the activity displaying the list_fragment, in put this in my activities onCreate function:
supportFragmentManager.beginTransaction()
.add(R.id.fragment_container, FragmentList::class.java, Bundle())
.commit()
The result looks like this:
The gray part is the empty_fragment and the white part is the list_fragment. For some reason, the activity clumsily displays them both. Even though I only have one FragmentContainerView:
<androidx.fragment.app.FragmentContainerView
android:id="@+id/nav_host_fragment"
android:name="androidx.navigation.fragment.NavHostFragment"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:defaultNavHost="true"
app:navGraph="@navigation/nav"
tools:layout="@layout/fragment_empty" />
Another problem I suspect is, even if I manage to do it this way, the startDestination would still be on my backstack. I can manually remove it at the same time that I set the list_fragment, however, this seems like the wrong way to use it.
When I tried to research the problem, I mostly get to tutorials and Stack Overflow questions where someone wants to navigate between two fragments within an activity. This is not exactly what I want. I will never switch from empty_fragment to list_fragment or vice versa. I just want the activity to display either when it's started, depending on a condition.
I'm fairly new to working with fragments and navgraphs, so I might scramble some things here; please take that into consideration.
To summarize:
- How can I display either one of two fragments in my activity when the activity is created?
- Is this the correct way to achieve this?
- What is the reason for the odd stacked display my activity built with the two fragments?
