Key Refactoring Techniques
Here are fundamental refactoring techniques that address common design smells.
Composing Methods
- Extract Method: Turns a cohesive sub-block of code from a long method into a cleanly named independent method.
- Inline Method: Removes an unnecessary delegating method when its implementation is as transparent as its name.
- Replace Temp with Query: Replaces a local temporary variable with a query method.
Organizing Class Responsibilities
- Extract Class: Splits an overloaded class by migrating related fields and operations into a separate class.
- Inline Class: Merges a class that has ceased to provide distinct value back into another class.
- Move Method / Move Field: Moves behavior or data to the class that consumes it most frequently.
- Pull Up Field / Method: Elevates common members shared across multiple subclasses to their shared superclass.
- Push Down Field / Method: Relocates members needed by only specific subclasses downward.
- Replace Conditional with Polymorphism: Removes
switch(type) or if-else type inspections by leveraging dynamic method dispatch across subclass implementations.
Tip: Interactive 18 Refactoring Techniques Cheatsheet
Explore all 18 standard Fowler refactoring techniques with side-by-side Java code transformations and visual Mermaid UML diagrams in the Refactoring Lab.
Exercise 1
Which refactoring technique replaces a switch on an object type code with polymorphic subclasses?
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Solution
Replace Conditional with Polymorphism, which delegates execution to subclass overridden methods via dynamic dispatch.