Apply Border color to button on Android

Use the <stroke> element. Add this xml file in res/drawable folder as button_border.xml:

<?xml version="1.0" encoding="utf-8"?>
  <shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="rectangle">
    <gradient android:startColor="#FFFFFF" 
       android:endColor="#00FF00"
       android:angle="270" />
    <corners android:radius="3dp" />
    <stroke android:width="5px" android:color="#ffffff" />
 </shape>

then call this by in layout file

 

<Button
   android:id="@+id/button1"
   android:layout_width="wrap_content"
   android:layout_height="wrap_content"
   android:layout_margin="10dp"
   android:background="@drawable/button_border"
   android:text="Button" 
/>