validator.py is a tool for ensuring that data conforms to certain sets of rules, called validations. A validation is essentially a schema for a dictionary, containing a list of rules for each key/value pair in the dictionary you want to validate. This is intended to fill a similar use case to form validations in WTForms or Rails, but for general sources of data, not just Web forms.
Android Saripaar is a simple, yet powerful rule-based UI validation library for Android. It following features declarative style validation powered by Annotations, synchronous and asynchronous validations (you don't have to worry about threading), compatibility with Stock Android Widgets, custom view dependencies, quick setup (just download the jar and include it in your libs project folder), removal of most of your validation logic from your code, and compatibility with other annotation frameworks such as AndroidAnnotations, RoboGuice, etc.,