Lambda Expressions

Chapter 15

Lambda Expressions

During Java’s ongoing development and evolution, many features have been added since its original 1.0 release. However, two stand out because they have profoundly reshaped the language, fundamentally changing the way that code is written. The first was the addition of generics, added by JDK 5. (See Chapter 14.) The second is the lambda expression, which is the subject of this chapter.

Added by JDK 8, lambda expressions (and their related features) significantly enhance Java because of two primary reasons. First, they add new syntax elements that increase the expressive power of the language. In the process, they streamline the way that certain common constructs are implemented. Second, the addition of lambda expressions resulted in new capabilities being incorporated into the API library. Among these new capabilities are the ability to more easily take advantage of the parallel processing capabilities of multi-core environments, especially as it relates to the handling of for-each style operations, and the new stream API, which supports pipeline operations on data. The addition of lambda expressions also provided the catalyst for other new Java features, including the default method (described in Chapter 9), which lets you define default behavior for an interface method, and the method reference (described here), which lets you refer to a method without executing it.

Beyond the benefits that lambda expressions bring to the language, there is another reason why they constitute an important addition to Java. Over the past few years, lambda expressions have become a major focus of computer language design. For example, they have been added to languages such as C# and C++. Their inclusion in JDK 8 helps Java remain the vibrant, innovative language that programmers have come to expect.

In the final analysis, in much the same way that generics reshaped Java several years ago, lambda expressions are reshaping Java today. Simply put, lambda expressions will impact virtually all Java programmers. They truly are that important.