I want to make a button exactly like in this image

I want to use a xml file that will us
I haven't tried all of the answers here, but I believe some/all of them are works.
The accepted answer is also works, but it can be simplified. Since I love elegant and simple solution, I come up with my own solution. Basically, we just need to add radius big enough compared with your View width and height, so it will create a round corner. In this case I put 1000dp to make it safe. We don't even need to add android:shape="rectangle" at all.
Just follow these 2 simple steps:
Create an XML file in your drawable folder. For example let's name it bg.xml
Then you can use it in layout XML file as your View property android:background="@drawable/bg"
or directly in the code view.setBackgroundResource(R.drawable.bg)