The converter is a small app for Android. As a start it gives you an input field, then offers 4 buttons, each to change the above entered value to what you want (in my example from USD to EUR and INCH to CM). But feel free to change the units or add more/remove options.
It validates the input (atm to prevent the user from entering anything else than a number) in 2 ways: with a catch-clause and by defining the input type in the xml-elements. So, maybe you'd have to adjust that for your usage.
Nothing else to say - have fun with it!
