What types of design patterns do you know?

Design patterns are proven solutions to common development problems. Main types of patterns:

• Creational:

  • Singleton — guarantees a single instance of a class.
  • Factory Method — creating objects through an interface.
  • Abstract Factory — creating families of related objects.
  • Builder — step-by-step creation of a complex object.
  • Prototype — cloning objects.

• Structural:

  • Adapter — converts one class interface to another.
  • Decorator — dynamically adds behavior to an object.
  • Proxy — substitute for an object to control access.
  • Composite — tree structure of objects, where individual and composite objects are treated uniformly.
  • Facade — simplified interface to a complex system.

• Behavioral:

  • Observer — subscribing to events.
  • Strategy — choosing an algorithm at runtime.
  • Command — encapsulating a request as an object.
  • Iterator — sequential traversal of a collection.
  • State — changing object behavior when its state changes.

These patterns help write flexible, maintainable, and extendable code.