Rounded Button in Android

If you need a rounded button in Android, then create an XML file "RoundShapeBtn.xml" as drawable.

 <?xml version="1.0" encoding="utf-8"?>
  <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle" android:padding="10dp">   
  <solid android:color="#6E6E6E"/> <!-- this one is ths color of the Rounded Button -->
  <corners
   android:bottomRightRadius="10dp"
   android:bottomLeftRadius="10dp"
   android:topLeftRadius="10dp"
   android:topRightRadius="10dp"/>
</shape>

Add this to your button code:

android:background="@drawable/RoundShapeBtn"

You can do a rounded corner button without resorting to an ImageView.

A background selector resource, button_background.xml:

<?xml version="1.0" encoding="utf-8" ?> 
     <selector xmlns:android="http://schemas.android.com/apk/res/android">
     <!--  Non focused states 
      --> 
      <item android:state_focused="false" android:state_selected="false" android:state_pressed="false" android:drawable="@drawable/button_unfocused" /> 
      <item android:state_focused="false" android:state_selected="true" android:state_pressed="false" android:drawable="@drawable/button_unfocused" /> 
     <!--  Focused states 
      --> 
      <item android:state_focused="true" android:state_selected="false" android:state_pressed="false" android:drawable="@drawable/button_focus" /> 
      <item android:state_focused="true" android:state_selected="true" android:state_pressed="false" android:drawable="@drawable/button_focus" /> 
     <!--  Pressed 
      --> 
      <item android:state_pressed="true" android:drawable="@drawable/button_press" /> 
    </selector>

For each state, a drawable resource, e.g. button_press.xml:

<shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle">
  <stroke android:width="1dp" android:color="#FF404040" /> 
  <corners android:radius="6dp" /> 
  <gradient android:startColor="#FF6800" android:centerColor="#FF8000" android:endColor="#FF9700" android:angle="90" /> 
</shape>

Note the corners element, this gets you rounded corners!

Then set the background drawable on the button:

android:background="@drawable/button_background"

EDIT (9/2018): The same technique can be used to create a circular button. A circle is really just a square button with radius size set to 1/2 the side of the square

Additionally, in the example above the stroke and gradient aren't necessary elements, they are just examples and ways that you'll be able to see the rounded corner shape