1.Duplicated Code
Same expression in two methods of the same class: Extract Method
Same expression in two sibling subclass:Extract Method ,then Pull Up Field
Duplicated code in two unrelated classs:Extract Class/The method belongs only in one class and be invoked by the other class.
2.Long Method
A heuristic we follow is that whenever we feel the needd to comment something,we write a method instead(Extract Method).A good technology to identify the clumps of code to extract is to look for comments.Conditionals and loops also give signs for extraction.
3.Large Class
Extract Method
4.Long Parameters List
Replace Parameter with Method, Preserve Whole Object, Introduce Parameter Object.
5.Divergent Change
Extract Class.
6.Shotgun Surgery
Move Method, Move Field, Inline Class,.
7.Feature Envy
Move Method, Extract Method,.
8.Data Clumps
Extract Class, Introduce Parameter Object, Preserve Whole Object
9 Primitive Obseesion
10.Switch Statements
Extract Method
11.Parallel Inheritance Hierarchis
12.Lazy Class
13.Speculative Generality
14.Temporary Field
15.Message Chains
16.Middle Man
17.Inappropriate Intimacy
18.Alternative Classes with Different Interfaces
19.Incomplete Library Class
20.Data Class
21.Refused Bequest
Push Down Method and Push Down Field
22.Comments
