Java 8 facilitates several `functional interface`

in `java.util.function`

package. If we observe carefully, there are primarily four kinds of interfaces provided in this package, which are:

- Supplier
- Consumer
- Function
- Predicate

with the following signatures:

Supplier: () -> T Consumer: T -> () Predicate: T -> boolean Function: T -> R

In this post, alike `java.util.function`

package, we define a new functional interface, called `TriFrunction`

that accepts three arguments as parameters and returns the result after computation.

@FunctionalInterface public interface TriFunction { /** * Applies this function to the given arguments. * * @param t the first function argument * @param u the second function argument * @param s the third function argument * @return the function result */ R apply(T t, U u, S s); }

We can use this functional interface to compute the volume of a rectangular prism, by using following `lambda expression`

.

TriFunction volume = (x,y,z) -> x*y*z

To use this lambda expression in the volume computation, we can simply use following statement

volume.apply(2.4, 5.3, 10.4)

In this post, we have shown how to create a custom `functional interface`

and use it to write concise lambda expressions using Java 8. It seems quite straight-forward. If you have any question/remark, please leave a comment below.