This document discusses code refactoring and principles of good code design. It mentions Martin Fowler's statement that good programmers write code for humans to understand. It then lists and defines various code smells and refactoring techniques, noting which techniques are supported in Eclipse.

2. Any fool can write code that
computer can understand.
Good programmers write code
that humans can understand.
Martin Fowler - Refactoring

3. Calendar c = Calendar.getInstance();
c.set(2005, Calendar.NOVEMBER, 20);
c.getTime();
november(20, 2005);

7. bug

14. •
•
•
•

15. OCP
(Open-Closed Principle)

16. DRY
(Don’t Repeat Yourself)

17. SRP
(Single Responsibility Principle)

18. LSP
(Liskov Substitution Principle)

20. (duplicated code)

21. (long method)

22. (large class)

23. (long parameter list)

24. (divergent change)
class

25. (shotgun surgery)
classes

26. (feature envy)

27. (primitive obsession)

28. switch
(switch statements)

29. (lazy class)

30. (speculative generality)

31. (data class)

32. (refused bequest)

33. (comments)

42. (Extract Method)
Eclipse✔

43. (Inline Method)
Eclipse✔

44. (Inline Temp)
Eclipse✔

45. (Replace Temp with Query)
Eclipse✘

46. (Introduce Explaining Variable)
Eclipse✔

47. (Split Temporary Variable)
Eclipse✘

48. Remove Assignments to
Parameters
Eclipse✘

50. (Move Method)
Eclipse✔

51. (Move Field)
Eclipse✔

52. (Extract Class)
Eclipse✔

54. (Replace Data Value with
Object)
Eclipse✘

55. (Replace Magic Number with
Symbolic Constant)
Eclipse✔

56. (Encapsulate Collection)
Eclipse✘

57. (Replace Type Code with
Class)
Eclipse✘

58. (Replace Type Code with
Subclasses)
Eclipse✘

59. State/Strategy
(Replace Type Code with State/
Strategy)
Eclipse✘

61. (Decompose Conditional)
Eclipse✔ (Use Extract Method)

62. (Consolidate Conditional
Expression)
Eclipse✔

63. (Consolidate Duplicate
Conditional Fragments)
Eclipse✘

64. (Replace Nested Conditional
with Guard Clauses)
Eclipse✘

65. (Replace Conditional with
Polymorphism)
Eclipse✘

66. null
(Introduce Null Object)
Eclipse✘

68. (Rename Method)
Eclipse✔

69. (Add Parameter)
Eclipse✔

70. (Remove Parameter)
Eclipse✔

71. (Separate Query from
Modifier)
Eclipse✔ (extract two methods and rename)

72. (Parameterize Method)
Eclipse✘

73. (Preserve Whole Object)
Eclipse✘

74. (Introduce Parameter Object)
Eclipse✔

75. More…

81. One more thing…