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Learning Java Lambdas

You're reading from   Learning Java Lambdas An in-depth look at one of the most important features of modern Java

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Product type Paperback
Published in Mar 2017
Publisher
ISBN-13 9781787282087
Length 114 pages
Edition 1st Edition
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Author (1):
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Toby Weston Toby Weston
Author Profile Icon Toby Weston
Toby Weston
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Toc

Method references


I mentioned earlier that method references are kind of like shortcuts to lambdas. They're a compact and convenient way to point to a method and allow that method to be used anywhere a lambda would be used.

When you create a lambda, you create an anonymous function and supply the method body. When you use a method reference as a lambda, it's actually pointing to a named method that already exists; it already has a body.

You can think of them as transforming a regular method into a functional interface.

The basic syntax looks like this:

Class::method

or, a more concrete example:

String::valueOf

The part preceding the double colon is the target reference and after, the method name. So, in this case, we're targeting the String class and looking for a method called valueOf; we're referring to the static method on String.

public static String valueOf(Object obj) { ... }

The double colon is called the delimiter. When we use it, we're not invoking the method, just referencing it. So remember...

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