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Lack of Defensive Programming

Exposure of super state to child classes

Printing out error messages to console instead of logging

Classes with unclear focus

Unwieldy or unneeded comments

Use of exceptions to control program flow

Throwing of ambiguous exceptions

Use parameter objects instead of long method signatures

Never Duplicate Code

Return nulls from methods

Null Object pattern

onus is then on the callee to check the result is not null before using the result

client then doesn't have to check for nulls

empty map should be returned

Refactoring: Improving the Design of Existing Code

 Working Effectively with Legacy Code