How to use parallel streams for concurrent computation in Java?

How to use parallel streams for concurrent calculations in Java? Create parallel streams: Use the Stream.parallel() method. Perform operations: Use parallel streams to perform common operations such as mapping, aggregation, and filtering, applying them in parallel to each element. Parallel Computing: Parallel streams perform operations in parallel, improving performance, especially for large data sets.

How to use parallel streams for concurrent calculations in Java

Introduction

Parallel streams are a powerful tool in Java that allow developers to parallelize computations into multiple threads, thereby improving performance. This article will introduce how to use parallel streams in Java and provide a practical case for you to understand.

Using Parallel Streams

To create parallel streams, you need to use theStream.parallel()method. This method returns a stream with parallel execution capabilities. The following code snippet demonstrates how to create a parallel stream:

List numbers = List.of(1, 2, 3, 4, 5, 6, 7, 8, 9, 10); Stream parallelStream = numbers.stream().parallel();

Perform operations using parallel streams

Now that you have created a parallel stream, you can use common stream operations to Perform parallel computations. Here are examples of using parallel streams to perform some common operations:

• Parallel mapping:Apply a function to each element using themap()method.
• Parallel aggregation:Use thereduce()method to combine elements into a single result.
• Parallel filtering:Use thefilter()method to filter out elements that do not meet specific conditions.

For example, the following code snippet uses parallel streams to map each number to its square:

List squaredNumbers = parallelStream.map(n -> n * n).toList();

You can also use parallel streams to perform more complex parallel calculations. Note that parallel streams do not guarantee operations in a specific order.

Practical Case

Let us understand the powerful function of parallel streaming through a practical case. Consider a scenario where you need to perform complex calculations on the elements of a large list. The following code snippet shows a program that computes the factors of each integer in a list:

List numbers = List.of(1, 2, 3, 4, 5, 6, 7, 8, 9, 10); // 使用串行流计算因子 List> factors = numbers.stream() .map(n -> getFactors(n)) .toList(); // 使用并行流计算因子 List> parallelFactors = numbers.stream() .parallel() .map(n -> getFactors(n)) .toList();

In the above example,getFactors()is a method that computes the factors of a given number. By using parallel streams, the program can parallelize calculations to multiple threads, significantly improving performance, especially when the list is large.

Conclusion

Parallel streams are a powerful tool in Java that allow developers to easily parallelize computations, thereby improving performance. You can easily add parallel functionality to your application by using theStream.parallel()method and common stream operations.

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