Code Smells

From Martin Fowler's excellent book, Refactoring: Improving the Design of Existing Code. More descriptions can be found here.

• Duplicated Code
• Long Method
• Large Class
• Long Parameter List
• Divergent Change
• Shotgun Surgery
• Feature Envy
• Data Clumps
• Primitive Obsession
• Switch Statements
• Parallel Inheritance Hierarchies
• Lazy Class
• Speculative Generality
• Temporary Field
• Message Chains
• Middle Man
• Inappropriate Intimacy
• Alternative Classes with Different Interfaces
• Incomplete Library Class
• Data Class
• Refused Bequest
• Comments

• Duplicate code: identical or very similar code exists in more than one location.
• Large method: a method, function, or procedure that has grown too large.
• Large class: a class that has grown too large, see God object.
• Feature envy: a class that uses methods of another class excessively.
• Inappropriate intimacy: a class that has dependencies on implementation details of another class.
• Refused bequest: a class that overrides a method of a base class in such a way that the contract of the base class is not honored by derived class. See Liskov substitution principle.
• Lazy class: a class that does too little.
• Duplicated method: a method, function, or procedure that is very similar to another.
• Contrived Complexity: forced usage of overly complicated design patterns where simpler design would suffice.

Checkstyle, PMD and FindBugs for Java, to automatically check for certain kinds of code smells.