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- Can an application have multiple design patterns?
- Can we use each design pattern only once per application?
- Which pattern can make unrelated classes to work together in a single program?
- Which design pattern should be used to notify multiple objects about state changes of a single object?
Can an application have multiple design patterns?
You do not have to use one pattern for every piece of functionality. In fact, many pieces of functionality don't use patterns at all, and some pieces will use multiple patterns.
Can we use each design pattern only once per application?
Design patterns is used to solve specific programming problems. They are not used to architecture your applications. 1) Can I have multiple design patterns in the application? Yes.
Which pattern can make unrelated classes to work together in a single program?
Structural Patterns - Adapter Pattern
The Adapter pattern is used so that two unrelated interfaces can work together. The joining between them is called an Adapter. This is something like we convert interface of one class into interface expected by the client.
Which design pattern should be used to notify multiple objects about state changes of a single object?
The Observer Pattern (also known as Publish-Subscribe Pattern) is a behavioral design pattern which defines a one-to-many relationship between objects such that, when one object changes its state, all dependent objects are notified and updated automatically.
