Db... files...???

As said before I am a newbie.
In the program I’m doing should I save data: time, money and contacts that occur every day.
If the computer is shut down I would like the data was saved.
I would first go ahead ask what the method that I must follow. The easiest for a beginner, but also fairer: database? files on your computer?
Thanks a lot

For what you are doing database is the way to go.

And sorry… what type of database i have to choose?

Will the data be used by a single person or shared by several people? Single = SQLiteDatabase. Shared = PostgreSQLDatabase (or mysql or ms sql server or … your choice).