RecyclerView offers a convenient way to preview the layout in Android Studio's tab called Design:
tools:itemCount
Is there any equivalent for ExpandableListView?
I assume the answer is "no" because I found that a different tool, tools:listitem does work for ExpandableListView. I believe that's explained by its documentation, "Intended for: <AdapterView> (and subclasses like <ListView>)".
Yes, you are right. Each tools: attribute belongs to different class.
You could integrate these two attributes like below.
The main layout:
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingLeft="8dp"
android:paddingRight="8dp"
android:paddingTop="8dp"
android:paddingBottom="8dp"
tools:context=".MainActivity">
<ExpandableListView
android:id="@+id/expandableListView"
tools:listitem="@layout/sample_list_item" //notice this line
android:layout_height="match_parent"
android:layout_width="match_parent"
android:indicatorLeft="?android:attr/expandableListPreferredItemIndicatorLeft"
android:divider="@android:color/darker_gray"
android:dividerHeight="0.5dp" />
</RelativeLayout>
The sample_list_item layout:
<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.RecyclerView xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
tools:itemCount="3" //notice this line
android:layout_width="match_parent"
android:layout_height="match_parent">
</android.support.v7.widget.RecyclerView>
Now you will see in preview as below fig:
notice there are three items shown.