Functional interfaces must have exactly one abstract method, which allows them to be used as targets for lambda expressions and streamlines functional programming in Java.
Lambda expressions enable developers to implement functional interfaces concisely, avoiding boilerplate code from anonymous class implementations and enhancing code readability.
Functional interfaces not only serve a theoretical purpose but also lead to practical applications in Java, particularly in collections and stream processing.
By allowing developers to pass behavior as parameters, functional interfaces simplify code and are particularly advantageous when performing operations on large data collections.
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