Можешь перечислить ключевые характеристики функциональных интерфейсов в программировании?

Functional interfaces in Java are interfaces with exactly one abstract method, which allows them to be used as target types for lambda expressions and method references.

Key characteristics:

• One abstract method (SAM - Single Abstract Method).
• Can contain default methods with implementations.
• Can contain static methods.
• Annotated with @FunctionalInterface (not mandatory, but recommended for verification).
• Enable writing more concise and expressive code using lambdas.

Example:

@FunctionalInterface
public interface Converter<F, T> {
    T convert(F from);
}

// Usage
Converter<String, Integer> stringToInteger = Integer::valueOf;
int number = stringToInteger.convert("123");