Android, How to make an element always visible?

Question

Android

and so there are 2 lists, initially hidden, opened by pressing the buttons "A" and "B".
How to make it so that if there is a lot of information (lines) in list A, then the button "B" does not leave the screen, but is at the bottom.

ps lists are mutually closed on click i.e. if A is open then B is closed and vice versa

Answer 1

RelativeLayout, something like this:

<RelativeLayout
  android:layout_width="match_parent"
  android:layout_height="match_parent">

  <Button
    android:id="@+id/button1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentTop="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

  <ListView
    android:id="@+id/list1"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_below="@+id/button1"
    android:layout_above="@+id/button2"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

  <Button
    android:id="@+id/button2"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_above="@+id/list2"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

  <ListView
    android:id="@+id/list2"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_alignParentBottom="true"
    android:layout_alignParentLeft="true"
    android:layout_alignParentStart="true" />

</RelativeLayout>