Different ways to store (and retrieve) data on Android
Using the Android SharedPreferences mechanic to store data in what are essentially name-value pairs. The nice thing about this approach is that Android has some baked-in mechanisms for viewing/editing this data, making it an excellent choice for application-wide settings.
Open and close a file stream on Android. We use a java.util.Properties instance to give the file some simple structure and formatting, as is common with a lot of Java projects.
Same as fileio, except we use JSON storage for the data being stored. This is to show off how we combine local file storage and the use of the JSON classes Android provides.
Java's Object Serialization Specification, while deeply maligned by many in the Java community, makes for a simple-yet-powerful way to store/load complex object graphs or collections to disk.
Data often finds itself stored in a relational database, and data on Android can do the same if desired; as a matter of fact, much of the data that is stored by the pre-installed apps is stored in SQLite databases, which have been an option on Android since API 1. This sample shows how to use SQLite to write SQL directly; other classes in the Android library can abstract away the SQL-ness, but it's generally useful to know how to run a SQL statement directly (and harvest the results).
Note that using SQLite to store "servername" and "port" is really overkill and somewhat clumsy; this will be true for just about any "database", but still serves to show how to connect to the database, issue a query, and harvest the results.
One of the popular "NoSQL" databases that challenge the relational database for ownership of data in the server room, MongoDB is a document database that uses a binary protcol (BSON) to communicate between client and server. This sample shows how to use the MongoDB Kotlin (coroutine) driver--which uses a binary TCP/IP protocol, not HTTP/REST--to connect to a MongoDB instance running on your local laptop. To work against a cloud-hosted database, all that should need to change is the mongodb URL in the MainActivity. MongoDB must be running and available (on the default port, 27017) to the emulator for this sample to work--if it isn't, the app will crash.
Note that using MongoDB to store "servername" and "port" is really overkill and somewhat clumsy; this will be true for just about any "database", but still serves to show how to connect to the database, issue a query, and harvest the results.