Introduction - If you have any usage issues, please Google them yourself
The owner of a transport company to develop a vehicle management system Zhansan abstract parent class vehicle has a vehicle subclass of vehicles designed to a specific class, a total of a dozen. At first the vehicle a total of 100, after the increase in truck truck and a sedan car, bulldozer bulldozer, venue of the stadium car, bus bus each. The number of each class cars need to have the same calculation car count () method and screen output method of print (), and the different start methods start (). Output in each boot method "a certain car start", such as "bus start. If you do not want each subclass overrides the count () method and print (), and each sub-class of each object to call the three methods to adapt to future increases do not want to, change the subclass need, how to do? The system is running two years later, the bus changed to electric cars and track cars, the need to increase the charging method in the corresponding class. Each charging method "a certain vehicle chargi