Java Core Technical notes for busy people (3, interfaces, and lambda expressions)

1. Interfaces are key object-oriented features: They let you specify what should be done without providing the implementation

Recently, the importance of functional programming for concurrency and event-driven programming has improved

All methods of the interface default to the public method, without the need to explicitly declare the

The implementation class must declare the interface methods public, otherwise they will be accessible at the package level by default. The interface requires the public level access, so an error occurs

If a class implements only certain methods of an interface, it must be decorated with an abstract

2. Convert to interface type

　　

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Java Core Technical notes for busy people (3, interfaces, and lambda expressions)