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This article mainly introduces "how to use Java8 API Stream". In daily operation, I believe many people have doubts about how to use Java8 API Stream. The editor consulted all kinds of materials and sorted out simple and easy-to-use operation methods. I hope it will be helpful to answer the doubts about "how to use Java8 API Stream". Next, please follow the editor to study!

Java8 added API Strem (stream), students who have not used it may not know what it does. Let's talk about the benefits that Stream brings to us. It makes it easier for us to operate on collections. In the past, we had to write a lot of tedious code to deal with data filtering, sorting, data aggregation, collection conversion and conversion between different data types. Since the advent of Strem, we no longer have to write troublesome processing logic, which can be solved by a few lines or dozens of lines of code in the past.

In Java 8, the collection interface has two ways to generate the flow:

Stream () − creates a serial flow for the collection.

ParallelStream () − creates a parallel flow for the collection.

1. Filter out empty data in List.

List strings = Arrays.asList ("a", "", "b", "c", "d", "", "e"); List filtered = strings.stream () .filter (string->! string.isEmpty ()) .subscription (Collectors.toList ())

The method of multiplying each value by 2 in 2.list can also convert between different generic List data.

List numbers = Arrays.asList (3, 2, 2, 3, 7, 3, 5); List squaresList = numbers.stream (). Map (Collectors.toList ())

3. Do data aggregation operation

List strings = Arrays.asList ("a", "", "b", "c", "d", "", "e"); int count = strings.stream (). Filter (string-> string.isEmpty ()). Count (); at this point, the study of "how to use Java8 API Stream" is over, hoping to solve everyone's doubts. The collocation of theory and practice can better help you learn, go and try it! If you want to continue to learn more related knowledge, please continue to follow the website, the editor will continue to work hard to bring you more practical articles!

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