Stream API

The Stream API is one of the significant additions to Java 8. It provides a more functional and declarative approach to process collections of data. Stream API allows you to perform various operations on data, such as filtering, mapping, sorting, and reducing, in a concise and expressive manner.

Benefits of Stream API

The Stream API offers several benefits:

• Code readability: Stream API provides a fluent and concise syntax, making your code more readable and expressive.
• Parallel processing: Stream API supports parallelism, enabling efficient processing of large datasets by leveraging multiple threads.
• Stream pipeline: With Stream API, you can chain multiple operations together to form a pipeline, where the output of one operation becomes the input for the next operation.
• Lazy evaluation: Stream API uses lazy evaluation, meaning operations are executed only when necessary, resulting in better performance.

Example: Filtering and Mapping

Let's consider an example of using the Stream API to filter and map elements from a List of integers.

1import java.util.Arrays;
2import java.util.List;
3
4public class Main {
5
6  public static void main(String[] args) {
7    List<Integer> numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
8
9    List<Integer> evenSquares = numbers.stream()
10      .filter(n -> n % 2 == 0)
11      .map(n -> n * n)
12      .collect(Collectors.toList());
13
14    System.out.println(evenSquares);
15  }
16
17}

In the above example, we create a List of integers and use the Stream API to filter only the even numbers and then square each number. Finally, we collect the result into a new List and print it.

Output:

1[4, 16, 36, 64, 100]

This example demonstrates how the Stream API simplifies the process of filtering and transforming data in a declarative style.

Java 8 Features

In addition to the Stream API, Java 8 introduced several other features that enhance the language and make it more powerful and expressive.

Some notable Java 8 features include:

• Lambda expressions: Lambda expressions enable the use of anonymous functions to write more concise and functional code.
• Functional interfaces: Java 8 introduced functional interfaces, which are interfaces with a single abstract method. They are used extensively with lambda expressions and provide a way to write code in a functional programming style.
• Default methods: Default methods allow interfaces to provide concrete implementations for methods. This feature enables backward compatibility and the addition of new methods to existing interfaces without breaking code that implements those interfaces.
• Optional: The Optional class provides a way to handle nullable values more effectively. It encourages a more explicit handling of null values, reducing the risk of NullPointerExceptions.
• Date and time API: Java 8 introduced a new Date and Time API, which is more comprehensive and flexible compared to the older java.util.Date and java.util.Calendar classes.

These are just a few examples of the new features introduced in Java 8. Exploring and understanding these features will help you write more modern and efficient code in Java.

Exercise

Now that you have learned about the Stream API and Java 8 features, it's time to practice! Write a program using Java 8 features to solve the FizzBuzz problem. The program should print the numbers from 1 to 100, but for multiples of 3, it should print 'Fizz', for multiples of 5, it should print 'Buzz', and for multiples of both 3 and 5, it should print 'FizzBuzz'.

Use the code snippet provided and replace the comment // replace with your Java logic here with your solution.