Tip calculator project for Android Couple of extras along with basic functionalities:

1. Using a NumberPicker control (instead of standard buttons) for choosing Tip %.
2. Tried changing theme for the app and styles in TipCalculator.Manifest file for changing the styles for NumberPicker (wanted to show + and - sign for the number picker)
3. All text values are in values/strings.xml for better localization
4. Implemented 2 event listeners upon which it reculates the tip amount and total amount: a) TextChangedListener for EditText control. If the Bill amount changes then update the total. b) ValueChangedListener for NumberPicker control. If the tip % changes then cupdate the tip amount and total.
5. From the UI perspective, tried nested layouts and implemented custom drawable shape for giving rounded border to the relative layout.