Java Functional Interfaces Cheat Sheet

java.util.function.md

Supplier       ()     -> x
Consumer       x      -> ()
BiConsumer     x, y   -> ()
Callable       ()     -> x throws ex
Runnable       ()     -> ()
Function       x      -> y
BiFunction     x, y   -> z
Predicate      x      -> boolean
UnaryOperator  x1     -> x2
BinaryOperator x1, x2 -> x3

References

Lambda Expressions and Functional Interfaces: Tips and Best Practices

Choosing a Functional Interface