Database design and android plot library.

Today I downloaded the latest stable release of android plot with the intent of learning how to set up simple graphs with static data and displaying them in a tabbed frame with in an android app. The API is fairly straight forward and there are a few tutorials on their wiki page with code snippets of the correct usage of the package. Using the samples from the wiki and what I have done so far, I added a simple X,Y graph showing fuel economy over time to the stats tab. For now the values are hard coded as the exercise was for the purpose of visualising what the graph looks like, and also for familiarising myself with the API should I chose to use it. It certainly looks well despite the fact that I haven't really messed about with the formatting of the default graphs.

Pretty Graphics!

When dealing with dates and adding them to a domain, they are put in an array as epochs which is the number of miliseconds since the date January 1, 1970. This will make storing dates easier in a database, but some method of converting string formatted dates to epochs will need to be investigated. I don't currently know if there is a method of doing it in any of the standard java classes.

The next thing I'll be working on is designing the database for storing information about transactions which can be adapted at a later point to store information about the individual models and makes of cars and their respective stats. So far the variables that will need to be stored as part of one fuel transaction are the total cost of the transaction, the current mileage on the odometer, how many liters were paid for and the date of the transaction. On the fuel tab I plan to have a list of all previous transactions which can be cleared if the user wants, or specific individual entries can be deleted from the database if they were entered incorrectly. I need to come up with a table design for the database that will allow me to expand on it in future when it comes to implementing other features of the app. Also I need to think about what kind of information I need to store about the users for the purpose of identifying the user or having multiple accounts or whether it is even needed.