align a central button to bottom of screen

Question

In my screen layout contain a central button, i want to align that button to bottom of the screen. I tried with some code, but it became terrific...

my xml code as follows

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

   <Button
       android:id="@+id/btnButton1"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="Button 1"/>

    <RelativeLayout 
       android:id="@+id/belowLayout"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:layout_alignParentBottom="true"
       >

    <Button
        android:id="@+id/btnButton2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentLeft="true"
        android:text="Left"/>

    <Button
        android:id="@+id/btnButton3"
        android:layout_width="75px"
        android:layout_height="50px"
        android:layout_centerHorizontal="true"
        android:text="..."/>

    <Button 
        android:id="@+id/btnButton4"
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:text="Right"/>

      </RelativeLayout>
 </RelativeLayout>

screen shot

thanks

Answer 1

Use layout_alignParentBottom="true" like this:

 <Button
        android:id="@+id/btnButton3"
        android:layout_width="75px"
        android:layout_height="50px"
        android:layout_centerHorizontal="true"
        android:layout_alignParentBottom="true"
        android:text="..."/>

Answer 2

Try this

<Button
        android:id="@+id/btnButton3"
        android:layout_width="75px"
        android:layout_height="50px"
        android:layout_centerHorizontal="true"
        android:layout_alignBottom="@+id/btnButton2"
        android:text="..."/>

Answer 3

You have to stop using px here. It might be the reason for your problem. Simply try it like this using dip,

 <Button
        android:id="@+id/btnButton3"
        android:layout_width="75dip"
        android:layout_height="50dip"
        android:layout_centerHorizontal="true"
        android:text="..."/>

EDIT 1

        <Button
        android:id="@+id/btnButton3"
        android:layout_width="75dip"
        android:layout_height="25dip"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:text="..."/>

dip-density independent Pixels.

Here is the output,

Answer 4

Use android:layout_centerInParent="true" like this:

<Button
    android:id="@+id/btnButton3"
    android:layout_width="75px"
    android:layout_height="50px"
    android:layout_marginTop="10dp"
    android:layout_centerInParent="true"
    android:layout_alignParentBottom="true"
    android:text="..."/>

Answer 5

<Button
android:id="@+id/btnButton3"
android:layout_width="75px"
android:layout_height="50px"
android:layout_centerHorizontal="true"
android:gravity="center"
android:layout_gravity="center_vertical|center_horizontal"
android:text="..."/>

Answer 6

为"@+id/btnButton3"添加android:layout_alignParentBottom="true" "@+id/btnButton3"