Abstract Factory — factory of factories

Abstract Factory is a pattern for creating families of related objects that must work together and stay consistent. The classic example is a UI toolkit. Imagine an app that runs on Windows and macOS. You need buttons, text fields, and scroll bars, but the Windows versions look different from the macOS versions. If developers can mix and match — a Windows button with a macOS text field — the interface looks broken. Abstract Factory prevents that. You define a GUIFactory interface with methods like createButton, createTextField, and createScrollBar. Then you implement two concrete factories, WindowsGUIFactory and MacGUIFactory, and each returns the matching set. The client code depends only on the GUIFactory interface, so you can switch the entire family by changing one line — which factory you instantiate. If the user is on Windows, you use WindowsGUIFactory and everything is Windows style; on macOS you swap to MacGUIFactory and everything matches. The key difference from Factory Method is that Factory Method creates one product, while Abstract Factory creates several related products. A backend example is JDBC: a driver creates a matching Connection, Statement, and ResultSet, all from the same vendor family, so swapping the driver gives you a consistent set for the new database. The mistake freshers make is confusing Abstract Factory with Factory Method. The giveaway is the word family — if you're creating multiple related objects that belong together and must stay consistent, it's Abstract Factory. Another mistake is grouping unrelated objects into one factory just because they're created in the same place. Use Abstract Factory only when consistency across the family actually matters.