Relativelayout align top and bottom

Question

I would like to align center horizontial & center vertical all 3 buttons as 1 button in my relativelayout!

I used LinearLayout with parameter android:layout_weight, but Buttons's height is modified. This is my layout file. Thanks!

<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:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".Main" >

<Button
    android:id="@+id/bt_singleColor"
    android:layout_width="150dp"
    android:layout_height="100dp"
    android:layout_centerHorizontal="true"
    android:layout_margin="@dimen/button_margin"
    android:background="@drawable/button_circle"
    android:padding="@dimen/button_padding"
    android:text="@string/button_01"
    android:textColor="@color/button_text_color" />

<Button
    android:id="@+id/bt_shake"
    android:layout_width="150dp"
    android:layout_height="100dp"
    android:layout_below="@+id/bt_singleColor"
    android:layout_centerHorizontal="true"
    android:layout_margin="@dimen/button_margin"
    android:background="@drawable/button_circle"
    android:padding="@dimen/button_padding"
    android:text="@string/button_02"
    android:textColor="@color/button_text_color" />

<Button
    android:id="@+id/bt_autoColor"
    android:layout_width="150dp"
    android:layout_height="100dp"
    android:layout_below="@+id/bt_shake"
    android:layout_centerHorizontal="true"
    android:layout_margin="@dimen/button_margin"
    android:background="@drawable/button_circle"
    android:padding="@dimen/button_padding"
    android:text="@string/button_03"
    android:textColor="@color/button_text_color" />

Answer 1

You can use something like

<RelativeLayout to match parent or fill parent>
<LinearLayout with wrap_content and layout centerInParent>
<Button/>
<Button/>
<Button/>
</LinearLayout>
</RelativeLayout>

meaning that the LinearLayout is centered absolutely in the Relative layout and you can play with this alignment if you want something else. While for the Linearlayout you have wrap_content to detect its size based on the buttons size, margin and padding. Also don't forget about orientation for LinearLayout.