How to make a round button?

Create an xml file named roundedbutton.xml in drawable folder

<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android" 
android:shape="rectangle">
    <solid android:color="#eeffffff" />
    <corners android:bottomRightRadius="8dp"
        android:bottomLeftRadius="8dp"  
        android:topRightRadius="8dp"
        android:topLeftRadius="8dp"/>
</shape>

Finally set that as background to your Button as android:background = "@drawable/roundedbutton"

If you want to make it completely rounded, alter the radius and settle for something that is ok for you.

If using Android Studio you can just use:

<?xml version="1.0" encoding="utf-8"?>
    <shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">
        <solid android:color="#FFFFFF"/>

    </shape>

this works fine for me, hope this helps someone.

1. Create a drawable/button_states.xml file containing:

   <?xml version="1.0" encoding="utf-8"?>
   <selector xmlns:android="http://schemas.android.com/apk/res/android">
       <item android:state_pressed="false"> 
           <shape android:shape="rectangle">
           <corners android:radius="1000dp" />
           <solid android:color="#41ba7a" />
           <stroke
               android:width="2dip"
               android:color="#03ae3c" />
           <padding
               android:bottom="4dp"
               android:left="4dp"
               android:right="4dp"
               android:top="4dp" />
           </shape>
       </item>
       <item android:state_pressed="true"> 
           <shape android:shape="rectangle">
           <corners android:radius="1000dp" />
           <solid android:color="#3AA76D" />
           <stroke
               android:width="2dip"
               android:color="#03ae3c" />
           <padding
               android:bottom="4dp"
               android:left="4dp"
               android:right="4dp"
               android:top="4dp" />
           </shape>
       </item>
   </selector>
   

2. Use it in button tag in any layout file

   <Button
       android:layout_width="220dp"
       android:layout_height="220dp"
       android:background="@drawable/button_states"
       android:text="@string/btn_scan_qr"
       android:id="@+id/btn_scan_qr"
       android:textSize="15dp"
   />
   

Markushi's android circlebutton:

(This library is deprecated and no new development is taking place. Consider using a FAB instead.)

If you want a FAB looking circular button and you are using the official Material Component library you can easily do it like this:

<com.google.android.material.button.MaterialButton
    style="@style/Widget.MaterialComponents.ExtendedFloatingActionButton"
    app:cornerRadius="28dp"
    android:layout_width="56dp"
    android:layout_height="56dp"
    android:text="1" />

Result:

If you change the size of the button, just be careful to use half of the button size as app:cornerRadius.