Java Lambdas & Streams

Functional-style programming.

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A lambda is a short anonymous function: (a, b) -> a + b.

The Stream API processes collections in a pipeline:

filter(): keep matching items
map(): transform items
sorted(), limit(), distinct()
collect(Collectors.toList()) or toList(), sum(), count(), average()

Key Takeaways: Java Lambdas & Streams

Mastering Java Lambdas & Streams helps you write clean and reliable Java code. Follow standard conventions, test edge cases, and keep logic simple. Try running the code example below and complete the exercises to build confidence.

Java Lambdas & Streams Code Example

Java

import java.util.*;

public class Main {
    public static void main(String[] args) {
        List<Integer> marks = List.of(72, 95, 58, 88, 64);

        List<Integer> passed = marks.stream()
            .filter(m -> m >= 60)
            .sorted(Comparator.reverseOrder())
            .toList();

        double avg = marks.stream().mapToInt(Integer::intValue).average().orElse(0);

        System.out.println(passed);
        System.out.println("Average: " + avg);

        List.of("ali", "sara").forEach(n -> System.out.println(n.toUpperCase()));
    }
}

Output