A Full WaterVehicle, Ship, etc. 
This exercise comprises of a base class WaterVehicle. It will also have a class Ship, a class Boat, a class WaterAirplane, and a class Submarine.
updateSpeed(int) will update the speed to a valid speed - higher than minSpeed and lower than maxSpeed
You can choose what to use.
Note: Ship, Boat, and WaterAirplane should extend WaterVehicle.
When you are done, you can create a main class to run your program. For example, the main class could create an instance of WaterAirplane and try using the methods.
Submit Exercises 
If you have any ideas for exercises that are related to what beginners learned in the fundamentals section, feel free to put them here. Note: It will look nice if you put them before this and make their name with a title1 (1 equal sign).