Stream API and Java 8 Features

In Java 8, several new features were introduced to the language, including the Stream API and various functional programming enhancements. These features allow developers to write more concise and readable code, especially when dealing with collections and data processing.

The Stream API provides a fluent and functional approach to work with a sequence of elements. It allows you to perform operations such as filtering, mapping, and reducing on streams of data. Streams are a powerful tool for handling large collections or performing complex data transformations.

Here's an example that demonstrates the use of the Stream API to calculate the sum of even numbers from a list:

Note: The code snippet below uses the Java 8 lambda syntax for inline function definitions.

1class Main {
2  public static void main(String[] args) {
3    // Create a list of numbers
4    List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);
5
6    // Use Stream API to calculate the sum of even numbers
7    int sum = numbers.stream()
8                    .filter(n -> n % 2 == 0)
9                    .mapToInt(n -> n)
10                    .sum();
11
12    System.out.println("Sum of even numbers: " + sum);
13  }
14}

In the code above, we first create a list of numbers. We then use the stream() method to convert the list into a stream of elements. Next, we apply a filter operation to keep only the even numbers, followed by a mapping operation to convert the stream of integers to a stream of IntStream. Finally, we use the sum() method to calculate the sum of the numbers in the stream.

The output of the above code will be:

1Sum of even numbers: 6

The Stream API is a powerful tool for working with collections and data processing in a concise and readable manner. It is worth exploring further and leveraging its capabilities in your Java development.

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class Main {

  public static void main(String[] args) {

    // Create a list of numbers

    List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5);

​

    // Use Stream API to calculate the sum of even numbers

    int sum = numbers.stream()

                    .filter(n -> n % 2 == 0)

                    .mapToInt(n -> n)

                    .sum();

​

    System.out.println("Sum of even numbers: " + sum);

  }

}