entity/Article.java

@Entity
public class Article {
    (중략)
    @Column
    private String content;
    // Article 생성자 추가

    public Article(Long id, String title, String content) {
        this.id = id;
        this.title = title;
        this.content = content;
    }

    // toString() 메서드 추가

    @Override
    public String toString() {
        return "Article{" +
                "id=" + id +
                ", title='" + title + '\'' +
                ", content='" + content + '\'' +
                '}';
    }

}