Review arrays, arrays and methods of how to store in memory is the problem, some little understood.
Review of object-oriented thinking, is object-oriented, the class definition, an object is instantiated, the constructor, and a form definition javabean class. Process-oriented is to solve problems, object-oriented is to find an object to help you solve the problem. Scanty,
Review the interfaces and polymorphism, a lot of things can only say ,, received part of it. I only know a similar interfaces and classes, interfaces, save a bunch of methods, abstract methods, static methods and the default method, use the class to implement the interface. This interface is very important, I found after the spring inside the interface is the key, and then slowly digest it!