Stream API and Java 8 Features

In Java 8, significant enhancements were made to the language, and one of the most notable additions was the Stream API. The Stream API provides functional-style operations on streams of elements, making it easier to perform operations such as filtering, mapping, and reducing on collections.

What is a Stream?

A Stream, in Java, represents a sequence of elements that can be processed in parallel or sequentially. It is not a data structure like arrays or lists but rather a concept that allows you to process data in a declarative way.

Stream Operations

Streams support two types of operations: intermediate and terminal operations. Intermediate operations are operations that transform or filter the elements of a stream and return a new stream. Examples of intermediate operations include filter(), map(), and sorted(). Terminal operations are operations that produce a result or a side-effect, such as forEach(), collect(), and reduce().

Example Using Stream API

Let's take a look at an example that demonstrates the use of the Stream API to filter names starting with the letter 'A':

1import java.util.Arrays;
2import java.util.List;
3import java.util.stream.Collectors;
4
5public class Main {
6
7    public static void main(String[] args) {
8        List<String> names = Arrays.asList("Alice", "Bob", "Charlie", "David");
9
10        // Filter names starting with 'A'
11        List<String> filteredNames = names.stream()
12                .filter(name -> name.startsWith("A"))
13                .collect(Collectors.toList());
14
15        System.out.println(filteredNames);
16    }
17
18}

In this example, we have a list of names and we use the Stream API to filter the names starting with the letter 'A'. The result is a new list containing only the filtered names.

Benefits of Stream API

The Stream API offers several advantages:

• Readability: The Stream API provides a more concise and expressive way to write code compared to traditional loop constructs.
• Parallel Execution: The Stream API allows for easy parallel execution of operations, providing performance improvements on multi-core systems.
• Lazy Evaluation: Streams use lazy evaluation, meaning that elements are processed as they are needed, which can result in improved performance and reduced memory usage.

The Stream API and Java 8 features are powerful tools that can greatly simplify your code and make it more readable. It is important to familiarize yourself with these concepts to take full advantage of the capabilities they offer in modern Java development.

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import java.util.Arrays;

import java.util.List;

import java.util.stream.Collectors;

​

public class Main {

​

    public static void main(String[] args) {

        List<String> names = Arrays.asList("Alice", "Bob", "Charlie", "David");

​

        // Filter names starting with 'A'

        List<String> filteredNames = names.stream()

                .filter(name -> name.startsWith("A"))

                .collect(Collectors.toList());

​

        System.out.println(filteredNames);

    }

​

}