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Learning Java Lambdas

Learning Java Lambdas

By : Toby Weston
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Learning Java Lambdas

Learning Java Lambdas

By: Toby Weston

Overview of this book

In this short book, we take an in-depth look at lambdas in Java, and their supporting features. The book covers essential topics, such as functional interfaces and type inference, and the key differences between lambdas and closures. You will learn about the background to functional programming and lambdas, before moving on to understanding the basic syntax of lambdas and what differentiates these anonymous functions from standard anonymous classes. Lastly, you'll learn how to invoke lambdas and look at the bytecode generated. After reading this book, you'll understand lambdas in depth, their background, syntax, implementation details, and how and when to use them. You'll also have a clear knowledge of the difference between functions and classes, and why that's relevant to lambdas. This knowledge will enable you to appreciate the improvements to type inference that drive a lot of the new features in modern Java, and will increase your understanding of method references and scoping.
Table of Contents (5 chapters)
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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...

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Learning Java Lambdas
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