java/w10/ArticleRepository.java

package w10;
public class ArticleRepository {
    private final List<Article> articles = new ArrayList<>();

    public void add(Article article) {
        if (article == null) {
            throw new IllegalArgumentException("Article cannot be null");
        }
        articles.add(article);
    }

    public void addAll(List<Article> newArticles) {
        if (newArticles == null) {
            return;
        }

        for (Article article : newArticles) {
            if (article != null) {
                articles.add(article);
            }
        }
    }

    public List<Article> getAll() {
        return Collections.unmodifiableList(articles);
    }

    public int size() {
        return articles.size();
    }

    public void clear() {
        articles.clear();
    }
}