RecyclerView滚动异常求助：从二级Activity返回后出现滚动问题

Hey there! Let's tackle this RecyclerView scrolling issue you're facing after navigating back from the second Activity. I've run into similar headaches before, so here are the most common fixes to try out:

1. Missing Layout Manager Scroll State Preservation #

When you navigate back to the first Activity, the RecyclerView might lose its scroll position because you aren't saving and restoring the LayoutManager's state properly. Even though Android saves some view states by default, custom data loading or LayoutManager reinitialization can overwrite this.

Fix: Save the state in onSaveInstanceState and restore it when the Activity resumes:

private var layoutManagerState: Parcelable? = null

override fun onSaveInstanceState(outState: Bundle) {
    super.onSaveInstanceState(outState)
    // Save the current scroll position
    layoutManagerState = recyclerView.layoutManager?.onSaveInstanceState()
    outState.putParcelable("RECYCLER_SCROLL_STATE", layoutManagerState)
}

override fun onRestoreInstanceState(savedInstanceState: Bundle) {
    super.onRestoreInstanceState(savedInstanceState)
    layoutManagerState = savedInstanceState.getParcelable("RECYCLER_SCROLL_STATE")
}

override fun onResume() {
    super.onResume()
    // Restore state only if data is already loaded
    if (layoutManagerState != null && recyclerView.layoutManager != null) {
        recyclerView.layoutManager?.onRestoreInstanceState(layoutManagerState)
    }
}

2. Repeating Data Loads & Adapter Reinitialization #

If you're re-fetching data or creating a new Adapter every time the Activity resumes, the RecyclerView will reset its scroll position (and possibly cause glitches). This happens because you're essentially re-building the list from scratch.

Fix: Add a flag to avoid redundant data loads and reuse your Adapter instance:

private var isDataLoaded = false
private lateinit var myAdapter: OptionsAdapter

override fun onCreate(savedInstanceState: Bundle?) {
    super.onCreate(savedInstanceState)
    // Initialize your views
    myAdapter = OptionsAdapter()
    recyclerView.adapter = myAdapter

    // Only fetch data on first launch
    if (!isDataLoaded) {
        fetchOptionsFromNetwork()
        isDataLoaded = true
    }
}

private fun fetchOptionsFromNetwork() {
    // Your network call logic here
    // On success:
    myAdapter.submitList(networkResponseData)
}

3. Incorrect ListAdapter Usage #

If you're using ListAdapter (from Jetpack), make sure you're using submitList() to update data instead of creating a new Adapter each time. Re-creating the Adapter forces the RecyclerView to rebind all items, breaking scroll continuity.

Key Note: Always keep a single instance of your Adapter attached to the RecyclerView, and only update its data set when needed.

4. Check Activity Launch Mode #

If you've modified the first Activity's launchMode in the manifest (e.g., singleTask or singleInstance), it might cause unexpected Activity recreation or state loss when navigating back.

Fix: Verify your AndroidManifest.xml entry for the first Activity uses the default standard launch mode:

<activity
    android:name=".FirstActivity"
    android:launchMode="standard"> <!-- This is the default, can omit if not modified -->
    <!-- ... other attributes -->
</activity>

Start with checking the scroll state preservation and redundant data loads—those are the most likely culprits here. Let me know if you need help narrowing it down further!

内容的提问来源于stack exchange，提问作者hyperCoder