Parallel Streams

In Java, parallel streams provide a convenient way to perform parallel processing on collections. Parallel streams allow you to split the elements of a stream into multiple chunks and process them concurrently across multiple threads.

To execute stream operations in parallel, you can convert a sequential stream to a parallel stream using the parallelStream() method. This enables the stream operations to be executed on multiple threads simultaneously.

Here's an example of using parallel streams to process a list of numbers:

1// Creating a list of numbers
2List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
3
4// Using sequential stream
5System.out.println("Sequential Stream:");
6numbers.stream()
7    .forEach(System.out::println);
8
9// Using parallel stream
10System.out.println("Parallel Stream:");
11numbers.parallelStream()
12    .forEach(System.out::println);

In this example, we have a list of numbers and we use both a sequential stream (stream()) and a parallel stream (parallelStream()) to process and print the numbers. The output shows that the elements are processed in parallel, potentially improving the processing speed.

It's important to note that not all stream operations are suitable for parallel processing. Some operations, such as forEachOrdered(), may introduce additional synchronization overhead and reduce the performance benefits of parallel streams. Therefore, it's recommended to analyze the specific use case and performance requirements before using parallel streams.

Parallel streams are a powerful feature of Java that can significantly improve the performance of processing collections in concurrent and multi-threaded environments. However, it's important to use them judiciously and consider the trade-offs between performance and complexity.

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class Main {

    public static void main(String[] args) {

        // Creating a list of numbers

        List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);

​

        // Using sequential stream

        System.out.println("Sequential Stream:");

        numbers.stream()

            .forEach(System.out::println);

​

        // Using parallel stream

        System.out.println("Parallel Stream:");

        numbers.parallelStream()

            .forEach(System.out::println);

    }

}