Use state mode to refactor switch statements

" use state mode to refactor switch statements "

The following code deals with multiple cases in a switch, and when the case becomes more or more and more or less logically, it produces bloated, hard-to-maintain code.

　　

State mode is often used to optimize this disadvantage of switch. Refactoring means one, using inheritance.

　　

Continue optimization, using state mode.

　　

The refactoring technique used here is called Replace Type Code with State/strategy. It is important to note that this modification is a burden on a small amount of code.

　　

　　

　　

Use state mode to refactor switch statements