[Search] Unable to apply search string to RecyclerView

[patrickfrei]

Description: I have below structure in my activity_main.xml, incl. SearchBar and SearchView, similar to the documentation. I'm using a ViewPager2 with fragments (one for each tab of the TabLayout, including each a RecyclerView list). Basically, the GUI looks like the Catalog app RecyclerView Demo.

<?xml version="1.0" encoding="utf-8"?>
<androidx.coordinatorlayout.widget.CoordinatorLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/main_content"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:fitsSystemWindows="true"
    android:layoutDirection="locale"
    android:textDirection="locale"
    tools:context=".MainActivity">

    <com.google.android.material.appbar.AppBarLayout
        android:id="@+id/appbar"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:stateListAnimator="@null"
        android:fitsSystemWindows="true">

        <com.google.android.material.appbar.MaterialToolbar
            android:id="@+id/toolbar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:minHeight="?attr/actionBarSize"
            app:layout_scrollFlags="scroll|enterAlways|snap"
            app:layout_scrollEffect="compress" />

        <com.google.android.material.tabs.TabLayout
            android:id="@+id/tabs"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:background="@android:color/transparent"
            android:contentDescription="@string/app_name"
            app:layout_scrollFlags="scroll|enterAlways"
            app:tabMode="scrollable" />

        <com.google.android.material.search.SearchBar
            android:id="@+id/search_bar"
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:hint="searchbar_hint" />

    </com.google.android.material.appbar.AppBarLayout>

    <com.google.android.material.search.SearchView
        android:id="@+id/search_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:hint="searchview_hint"
        app:layout_anchor="@id/search_bar">

        <androidx.recyclerview.widget.RecyclerView
            android:id="@+id/search_results_recycler_view"
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:scrollbars="vertical" />

    </com.google.android.material.search.SearchView>

    <androidx.viewpager2.widget.ViewPager2
        android:id="@+id/container"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:clipChildren="false"
        android:clipToPadding="false"
        app:layout_behavior="@string/appbar_scrolling_view_behavior" />

</androidx.coordinatorlayout.widget.CoordinatorLayout>

Expected behavior: This is how I understand the Material Design search functionality for my use case:

• I click on the SearchBar, the SearchView opens. I enter a search string, the original RecyclerView of the currently selected tab will be searched for the string and the results are shown in the RecyclerView with id search_results_recycler_view (i.e. the one within SearchView).
• With setOnEditorActionListener / SearchView.getText, I'm listening for the search string.

Setup:

• SearchBar and SearchView are defined in MainActivity
• RecyclerViews and adapters are defined in the fragments
• Custom adapter for RecyclerView has a getFilter() method implemented

The problem is that I'm not sure on how to... a) transfer the search string from SearchView to the original RecyclerView list of the currently selected tab and then... b) transfer the filtered list back to the RecyclerView with id search_results_recycler_view within SearchView.

Shall I use a ViewModel for each transfer part? Easy for a) where I can use String, but for b) it tricky as ViewModel doesn't allow an ArrayList<CustomAdapter>?

The Catalog RecyclerView Demo also doesn't show how to do that as all search results are hard-coded and have no association with the original text, so entering a search string has no effect.

Can you please share some insights (e.g. in the documentation) on how to implement this (best practice) or would you be able to amend the Catalog demo accordingly?

Source code: See above XML code.

Android API version: Tested on Android API 30-35

Material Library version: 1.13.0-alpha07

Device: Pixel 8 emulators, Nokia 7.2