What functional interfaces do you know?

• Predicate<T>: Accepts an argument of type T and returns a boolean value. Often used for filtering elements.
• Consumer<T>: Accepts an argument of type T and returns nothing. Used for performing actions on elements.
• Supplier<T>: Takes no arguments and returns a value of type T. Used for generating values.
• Function<T, R>: Accepts an argument of type T and returns a value of type R. Used for transforming values.
• UnaryOperator<T>: Extends Function<T, T>, accepts an argument of type T and returns a value of the same type.
• BinaryOperator<T>: Extends BiFunction<T, T, T>, accepts two arguments of type T and returns a value of the same type. Often used in reduction operations.
• BiPredicate<T, U>: Accepts two arguments of types T and U, returns a boolean value.
• BiConsumer<T, U>: Accepts two arguments of types T and U, returns nothing.
• BiFunction<T, U, R>: Accepts two arguments of types T and U, returns a value of type R.

Additionally, there are specialized functional interfaces for primitive types (IntPredicate, LongSupplier, DoubleConsumer, etc.) to avoid auto-boxing/unboxing, as well as interfaces with a return type of void (Runnable).