#streams code explainers

java

public List<String> collectTagsFromArticles(List<Article> articles) {
    return articles.stream()
        .flatMap(article -> article.getTags().stream())
        .map(String::trim)

Flattening nested data with Java streams

streams flatmap collectors

Intermediate 7 steps

java

public final class FileChecksum {
 
    private static final char[] HEX = "0123456789abcdef".toCharArray();

Streaming a SHA-256 file checksum in Java

hashing streams resource-management

Intermediate 7 steps

java

public Map<Long, List<Order>> ordersByCustomer(List<Order> orders) {
    return orders.stream()
            .collect(Collectors.groupingBy(Order::getCustomerId));
}

Grouping streams with Java Collectors

streams grouping collectors

Intermediate 5 steps

java

package com.example.logs;
 
import java.io.IOException;
import java.io.UncheckedIOException;

Counting HTTP statuses with Java streams

streams regex file-io

Intermediate 6 steps

java

public final class BusinessDays {
 
    private BusinessDays() {
    }

Counting business days between two dates in Java

date arithmetic utility class streams

Intermediate 7 steps

java

import java.util.ArrayList;
import java.util.Comparator;
import java.util.HashSet;
import java.util.List;

Three ways to deduplicate a list by key in Java

streams deduplication collectors

Intermediate 6 steps