Q:

Creating a tree like hierarchy of java objects

I'm trying to create a Manga app for Android where the each Chapter has its own Title,Publication Date, Description, etc. And each of said chapters belongs to a Manga object. Which would be a collection of Chapters and would include a list of the titles plus the Title of the Manga itself and the author('s) name(s). The data itself would be parsed from different webpages (but that's another mater).
My confusion is about the class declarations. (i.e. implements, extends)
Ive tried many things but as of right now my code consists of having chapters as an inner class like so:
public abstract class Manga implements MangaList {
public String name;
public String author;
public int chapters;

// names of the XML tags
static final String CHANNEL = "channel";
static final String PUB_DATE = "pubDate";
static final  String DESCRIPTION = "description";
static final  String LINK = "link";
static final  String TITLE = "title";
static final  String ITEM = "item";

private final URL feedUrl;

protected Manga(String feedUrl){
    try {
        this.feedUrl = new URL(feedUrl);
    } catch (MalformedURLException e) {
        throw new RuntimeException(e);
    }
}

protected InputStream getInputStream() {
    try {
        return feedUrl.openConnection().getInputStream();
    } catch (IOException e) {
        throw new RuntimeException(e);
    }
}

List<Chapter> Chapter;

public class Chapter implements Comparable<Chapter> {

    final SimpleDateFormat FORMATTER = 
            new SimpleDateFormat("EEE, dd MMM yyyy HH:mm:ss Z");
        private String title;
        private URL link;
        private String description;
        private Date date;

        public String getTitle() {
            return title;
        }

        public void setTitle(String title) {
            this.title = title.trim();
        }
        // getters and setters omitted for brevity 
        public URL getLink() {
            return link;
        }

        public void setLink(String link) {
            try {
                this.link = new URL(link);
            } catch (MalformedURLException e) {
                throw new RuntimeException(e);
            }
        }

        public String getDescription() {
            return description;
        }

        public void setDescription(String description) {
            this.description = description.trim();
        }

        public String getDate() {
            return FORMATTER.format(this.date);
        }

        public void setDate(String date) {
            // pad the date if necessary
            while (!date.endsWith("00")){
                date += "0";
            }
            date = "";
            try {
                this.date = FORMATTER.parse(date.trim());
            } catch (ParseException e) {
                throw new RuntimeException(e);
            }
        }

        public Chapter copy(){
            Chapter copy = new Chapter();
            copy.title = title;
            copy.link = link;
            copy.description = description;
            copy.date = date;
            return copy;
        }

        @Override
        public String toString() {
            StringBuilder sb = new StringBuilder();
            sb.append("Title: ");
            sb.append(title);
            sb.append('\n');
            sb.append("Date: ");
            sb.append(this.getDate());
            sb.append('\n');
            sb.append("Link: ");
            sb.append(link);
            sb.append('\n');
            sb.append("Description: ");
            sb.append(description);
            return sb.toString();
        }

        @Override
        public int hashCode() {
            final int prime = 31;
            int result = 1;
            result = prime * result + ((date == null) ? 0 : date.hashCode());
            result = prime * result
                    + ((description == null) ? 0 : description.hashCode());
            result = prime * result + ((link == null) ? 0 : link.hashCode());
            result = prime * result + ((title == null) ? 0 : title.hashCode());
            return result;
        }

        @Override
        public boolean equals(Object obj) {
            if (this == obj)
                return true;
            if (obj == null)
                return false;
            if (getClass() != obj.getClass())
                return false;
            Chapter other = (Chapter) obj;
            if (date == null) {
                if (other.date != null)
                    return false;
            } else if (!date.equals(other.date))
                return false;
            if (description == null) {
                if (other.description != null)
                    return false;
            } else if (!description.equals(other.description))
                return false;
            if (link == null) {
                if (other.link != null)
                    return false;
            } else if (!link.equals(other.link))
                return false;
            if (title == null) {
                if (other.title != null)
                    return false;
            } else if (!title.equals(other.title))
                return false;
            return true;
        }

        public int compareTo(Chapter another) {
            if (another == null) return 1;
            // sort descending, most recent first
            return another.date.compareTo(date);
        }
}

My question is if this is an appropriate format or if there is a simpler way to create a List of Mangas, each with its own set of Chapters?
EDIT: I've looked it up and decided that using an SQLite Database would be a much simpler way to keep track of the large amount of data I will be parsing.
This way I can maintain two databases. One for Manga titles and authors, and another for the chapters and relevant information. The Related chapters will be linked to the Manga in each table through a reference ID.

A:

I definitely think that there is an easier way to do this; however, it really depends on what you overall goal is. If you are trying to display this in a list you might consider using ListView, but if you are just using the data for content, then you can probably do something similar to what you have. Ultimately, you need to figure out what you are going to do with the app, then you can figure out the easiest way to implement it. Remember though: easier isn't always better. Try and think long term about your project as in who is going to be maintaining this, is it going to grow or shrink, and whether you will add features. 
As for extends and implements they are subclasses and interfaces, respectively and has different rules regarding it and more information can be found here: http://docs.oracle.com/javase/tutorial/java/concepts/interface.html
Best of luck!

