Avoiding invalid input entirely
Remember that with a mobile device, time is often a constraint for the user. For this reason (and for simple usability reasons) you should generally strive to avoid invalid input from your users entirely. Android provides you with several mechanisms with which to do this, and it's wise to make use of them at every opportunity. Generally, you will want to make use of widgets that avoid validation requirements. This is almost always an option in Android, and even when your requirements are more complex than simple type information, you can generally customize the widget to stop the user from breaking your validation rules.
Capturing date and time
As we've already discussed, when inputting date and time you should make ...