android, how to place a scroll view in the middle of the screen:

I'm trying to create a a screen layout of the following though:

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1. A line with some TextView in it
2. A scroll view where the user actions will add or remove View from
3. A buttons line.

I have no problem with 1. or 3. But 2. gives me troubles. My scheme is:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout 
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:id="@+id/mainX"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent" 
  android:orientation="vertical">
  <LinearLayout 
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:id="@+id/labels" 
    android:layout_weight="1">
  <!--Some text view of various sizes -->
  </LinearLayout>
  <ScrollView 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:id="@+id/dataScroll">
    <LinearLayout 
      android:id="@+id/dataShow" 
      android:layout_width="match_parent" 
      android:layout_height="wrap_content">
    </LinearLayout>
  </ScrollView>
  <LinearLayout 
    android:layout_width="match_parent" 
    android:layout_height="wrap_content" 
    android:id="@+id/buttons" 
    android:layout_weight="1">
  <!--some buttons-->
  </LinearLayout>
</LinearLayout>

When I run the program, the buttons line is in the middle of the screen and When I add element to the screen (using the addView on the dataShow layout), the frist one is added without a problem but after that I can't tell what is happening.

Thanks

---

I'm not exactly sure what you are trying to do.

It seems like you want to dynamically add items to the dataShow layout. Instead of using a ScrollView containing a LinearLayout, you should be using a ListView (vertical scrolling) or Gallery (horizontal scrolling) for your dataShow layout. This will provide the scroll functionality and allow you to add items dynamically to the list/gallery.

---

Try using a RelativeLayout, then align the header at the top, and the footer at the bottom. Set the ScrollView paddingBottom.

<?xml version="1.0" encoding="utf-8"?>

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <TextView
        android:id="@+id/header"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:background="@color/colorPrimary"
        android:paddingBottom="10dp"
        android:paddingTop="10dp"
        android:text="text"
        android:textAlignment="center"
        android:layout_centerHorizontal="true"
        android:layout_alignParentTop="true"/>

    <ScrollView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_below="@+id/header"
        android:layout_above="@+id/footer"
        android:paddingBottom="100dp">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="center main content"
            android:textAlignment="center"
            android:layout_centerHorizontal="true"
            android:layout_alignParentTop="true"/>

    </ScrollView>

    <RelativeLayout
        android:id="@+id/footer"
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:background="@color/colorPrimary"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true">

        <TextView
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:text="text"
            android:textAlignment="center"
            android:layout_centerHorizontal="true"
            android:layout_alignParentTop="true"/>

    </RelativeLayout>
</RelativeLayout>