Android Question Make API calls to google vision service authorizing APP

I'd like to use google vision service. I qould like do it in the same way as it is done here : https://www.b4x.com/android/forum/threads/google-maps.63930/#post-404386 for google maps.

I already have my app working but I am doing requests with APIKey for web. I would like to use an APIKey for Android.

Could you indicate to me the way ?

Thank you