Latest Android Studio will create & integrate a Basic Widget to your Application in 2 steps.

Right on your Application ==> New ==> Widget ==> App Widget

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https://i.stack.imgur.com/DL4ap.png

It will show a Screen like below & fill the fields

https://i.stack.imgur.com/3kJjF.png

Its Done.

It will create & integrate a basic HelloWorld Widget(Including Layout File , Meta Data File , Declaration in Manifest File etc.) to your Application.