Frequently used design patterns

Which patterns do you use the most? In which context/what for?

Comments

[Ricardo Costeira]

It really depends on the domain. The ones I used the most until now are:

• Singletons for core entity access (maintaining a database connection or a thread manager, for instance);
• Thread pool for thread managers;
• Observer and iterator (ReactiveX is awesome);
• Facade and repository for data access;
• Adapters for, well, adapting classes to interfaces (used them a lot on Android);
• Builders and factories for objects with many different parameters and versions;
• mvp and mvvm as architectural patterns;
• Strategy and template method because I hate seeing a lot of ifs and switches :)

[Rohith Kunnath]

Builder Pattern mostly used instead of typical getter/setter boilerplate codes. Gives me a clear idea on properties which are mandatory and optional. Really likes the way it helps a shareholder understand by just reading a couple of lines.

[Adrian B.G.]

Just a reminder, "most used" does not mean that they are used correctly, or they are the best solution :D

[Ricardo Costeira]

This. One of my greatest fears is will end up suffering from "design patternitis". I've had situations where the first solution I thought was to use some pattern, but later ended up not implementing it due to the impact on both performance or code complexity. Nevertheless, knowing the pattern helped me reach a better solution, so there's that.

Relevant link: jono.woaf.net/design-patterns/

[Adrian B.G.]

I think that if you go the other way around is better. Work your problem, and if in the end the solution ressemble a common pattern then you have a guideline how to implement it.
Your business logic is important, not the patterns.

[Ricardo Costeira]

Yes, I completely agree with you :) I was just talking about my own experience. I usually end up doing what you said, but it is quite common for me to easily recognize a pattern use case before starting any kind of implementation, and hence my fear.

[Jermaine]

Mixture of Factory for building different objects and Strategy in the context of writing pipeline logic as a means of reducing boilerplate from switch and if statements.

[Rémi B]

Great mix for "Workflow" like processes.

[K]

Components, for custom/aggregate UI elements and factory functions to create them :D

[Sergey]

Model–view–controller is an architectural pattern