To learn the good days did not last night, the succession and order a bit. Wanted to send something after finishing hexo blog up, but found that the command line and ineffective. A few days ago obviously is good, but these days no operation, online search, I did not hire the right solution, but unfortunately only heavy equipment. White is to toss, paste the following succession of first study notes
How to design the inheritance tree
1.Look for objects that have common attributions and behaviors.
2.Design a class that represents the common state and behavior.
3.Decide if a subclass needs behaviors(method implementations) that are specific to that particular subclass type.
4.Look for more opportunities to use abstraction, by finding two or more subclass that might need common behavior.
4 designing principles
1.DO use inheritance when one class is 大专栏 Inheritance Learning Notea more specific type of a superclass .
2.DO consider inheritance when you have behavior(implemented code) that should be shared among multiple classes of the same general type.
3.DO NOT use inheritance just so that you can reuse code from another class, if the relationship between the superclass and subclass violate either of the above two rules.
4.DO NOT use inheritance if the subclass and superclass do not pass the IS-A test.
Rules for overriding
The method are the contract
1.Arguments must be the same, and return types must be compatible.
2.The method can’t be less accessible.
Rules for overloading
1.The return types can be different.
2.you can’t change ONLY the return type.
3.You can vary the access levels in any direction.
Adhere to
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