streams

Java Streams API

The Java Streams API allows for functional-style operations on sequences of elements, such as collections. You can filter, map, and reduce elements in a declarative way.

Stream Example: Filter and Print

import java.util.Arrays;
import java.util.List;

public class StreamExample {
    public static void main(String[] args) {
        List numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
        
        // Filter even numbers and print them
        numbers.stream()
               .filter(n -> n % 2 == 0)
               .forEach(System.out::println);
    }
}

This example uses the stream() method to create a stream from the list of numbers, filters out even numbers, and prints each one.

Stream Example: Map and Reduce

import java.util.Arrays;
import java.util.List;

public class StreamExample {
    public static void main(String[] args) {
        List numbers = Arrays.asList(1, 2, 3, 4, 5, 6, 7, 8, 9, 10);
        
        // Square the numbers and sum them
        int sum = numbers.stream()
                          .map(n -> n * n)
                          .reduce(0, Integer::sum);
        
        System.out.println("Sum of squares: " + sum);
    }
}

This example demonstrates how to use the map() method to square the numbers and then use reduce() to sum them.