Border color on Android button

You can use this Online Button generator to Customize your button http://angrytools.com/android/button/

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

<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" 
/>

Try this

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="rectangle" >

<corners android:radius="1dp" />

<stroke
    android:width="2px"
    android:color="#ffffff" />

</shape>