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.

Class Hierarchy Transformations

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

Question

Which refactoring technique replaces a switch on an object type code with polymorphic subclasses?

Show solution ↓

Solution

Replace Conditional with Polymorphism, which delegates execution to subclass overridden methods via dynamic dispatch.