What database type to use?
"this bar code will lead to a screen on the medicine"
I recommend creating a API, by easy data editing, security, and avoid occupying unnecessary space on users devices.
To make the API you can use Laravel, Codeigniter, Slimphp among other PHP frameworks, in a vps LAMP. I recommend authenticating to get the API data.
To get the API data, use Volley
If you really want to store on the device, use the android Sqlite. Ex.: Example here
How not to create many activities?
You can use Fragments. Ex.: Example here
Overall, do Activities or Fragments that receive parameters and search for the information in the API.
Easier than that? No. That’s right. Database inside the device, if you want to have online availability and be always current, no accurate (although a cache is recommended by UX).
– Jefferson Quesado
I intend to connect this bank to the internet, because I need to add names, barcodes, and object information that I must always update.
– Pedro Henrique