Shulou(Shulou.com)06/03 Report--

This article introduces what the Java8 stream is, the content is very detailed, interested friends can refer to it, I hope it can be helpful to you.

Before we talk about stream, let's take a look at the collection. Why? As a new member of Java8, it has many similarities with collections, and they can also be transformed into each other. Collection is not only the Java language, any high-level development language has the concept of collection, collection, as the name implies, is a lot of data sets together, it is a container, at the same time, we can also use generics to limit the data types in the collection.

What is a stream?

Stream, as a new member of Java8, allows us to process data collections in a declarative manner. We can think of it as an advanced iterator that traverses a dataset. In addition, streams can be processed transparently in parallel, which eliminates the need to write any multithreaded code. We will talk in more detail about the parallelization of streams and streams later on.

From the above code, we can see:

1. The code is written declaratively. That is, what you want to do, not how.

2. You can use the operation chain. The method after filter can be clicked directly until it is finished.

From the above, we can briefly summarize the benefits of using streams:

1. Declarative: more concise and easy to read.

2. Reusable: more flexible.

3. Parallelism: better performance.

Introduction of flow

Above I saw a simple comparison between the stream and the set, so what is the bottom stream? We can simply describe the sequence of elements generated from a source that supports data processing operations. Let's analyze this sentence separately:

①, element sequence: it can access a set of ordered values of a specific element type, just like how to collect. But it is different from the collection, which is a kind of data structure, whose main purpose is to store data in a certain time and space. And the flow is mainly used to calculate. They are essentially different.

②, source: source. When a stream processes data, the source of the data, for example, a collection can be a source, or a file can be a source.

③, data processing operation: the stream is similar to our operation of the database when dealing with data, such as filter/map/sort and so on. When processing data, the stream can be executed sequentially or in parallel.

The flow has two obvious characteristics in the operation:

1. The assembly line. That is, the stream operation returns a stream, so that so many operations can be linked back all the time to form a pipeline.

2. Internal iteration. When the stream is processed, we do not see the process, it is executed behind the back. We can look back at the previous section, the police in the screening / sorting / mapping to the subsequent interception / conversion and so on how to complete, we can not see the implementation process.

Set and stream comparison

In Java8, collections and streams can be transformed into each other, but from a data point of view, collections can be traversed constantly, while streams can only be traversed once. Once traversal ends, it means that the stream is complete. If you want to process it again, you need to re-establish a stream object. If we reprocess a completed stream, an exception will be thrown.

So much for sharing about what the Java8 stream is. I hope the above content can be helpful to you and learn more. If you think the article is good, you can share it for more people to see.

Welcome to subscribe "Shulou Technology Information " to get latest news, interesting things and hot topics in the IT industry, and controls the hottest and latest Internet news, technology news and IT industry trends.