java - How to peek on an Optional?

Question

I want to use the fluent api of Optional and apply two Consumers to it.

I'm dreaming about something like this:

Optional.ofNullable(key)
    .map(Person::get)
    .ifPresent(this::printName)
    .ifPresent(this::printAddress); // not compiling, because ifPresent is void

How do I apply several Consumers to an Optional?

question from:https://stackoverflow.com/questions/43737212/how-to-peek-on-an-optional

Answer 1

Here's how you can implement the missing peek method for Optional:

<T> UnaryOperator<T> peek(Consumer<T> c) {
    return x -> {
        c.accept(x);
        return x;
    };
}

Usage:

Optional.ofNullable(key)
    .map(Person::get)
    .map(peek(this::printName))
    .map(peek(this::printAddress));