Example Java State Machine

Post.java

public class Post {
  
  public enum PostStatus {
    PENDING, PUBLISHED, UNPUBLISHED
  }
  
  private PostStatus status;
  
  public void post() {
    this.status = PostStatus.PUBLISHED;
  }
  
  public void unpublish() {
    this.status = PostStatus.UNPUBLISHED;
  }
  
  public void getStatus() {
    return this.status;
  }
  
}