Question

Following classes are created, no interface/abstract class for now:

1. Test – for creating test data
2. Music – should store all CDs
3. CD – should store Artist and CD title + all Songs
4. Artist – only contains String name
5. Song – contains default-constructor with (Artist anArtist, String songtitle, String Duration)
6. Duration – for the song duration and later calculations

i tried an ArrayList, but it gets overwritten when i add another CD. I need a data type that stores the data with a link to another array. for example: store artist and title of CD1 and link to another array that contains all songs from CD1.

thanks

code from class Test:

Artist aArtist = new Artist("artist1");
        CD aCD = myMusic.addCD(aArtist, "CD1");
        aCD.addSong(aArtist, "song1", "1:00");

aArtist = new Artist("artist2");
        CD aCD = myMusic.addCD(aArtist, "CD2"); //Overwrites arraylist from CD1
        aCD.addSong(aArtist, "song2", "2:00");

i changed my ArrayLists in class Music and class CD… i think there is an easier way to solve that tutorial, but here is the code: (outputs all saved songs and CD title)

class Music:

    import java.util.ArrayList;

public class Music {
    private ArrayList<CD> myCDs = new ArrayList<CD>();

    public CD addCD(Artist anArtist, String cdTitle) {

        CD aCD = new CD(anArtist, cdTitle);
        myCDs.add(aCD);
        return aCD;
    }

    public void showData() {

        for (int i = 0; i < myCDs.size(); i++) {
            for (int j = 0; j < myCDs.get(i).getMyCD().size(); j++) {

                System.out.println(myCDs.get(i).getMyCD().get(j).getSong());
            }
        }

    }
}

class CD:

  import java.util.ArrayList;

public class CD {
    private String cdTitle;
    private ArrayList<Song> myCD = new ArrayList<Song>();

    public CD(Artist aArtist, String cdTitle) {
        setMyCD(aArtist, cdTitle);
    }

    public ArrayList<Song> getMyCD() {
        return myCD;
    }

    public String getMyCDtitle() {
        return cdTitle;
    }

    public void setMyCD(Artist anArtist, String cdTitle) {
        this.cdTitle = anArtist.getName() + ": " + cdTitle;
    }

    public void addSong(Artist anArtist, String aTitle, String aDuration) {

        myCD.add(new Song(anArtist, aTitle, aDuration));

    }
}

class Song:

 public class Song {
    private String song;

    public String getSong() {
        return song;
    }

    public void setSong(String song) {
        this.song = song;
    }

    public Song(Artist anArtist, String songtitle, String aDuration) {
        Duration songDuration = new Duration(aDuration);
        setSong(anArtist.getName() + ": " + songtitle + " ("
                + songDuration.getSongDuration() + ")");

    }

}

in general: how would you solve such a project ?
i would appreciate every advice or uml diagram.

Answer 1

This may be a problem with aArtist = new Artist("artist2");
CD aCD = myMusic.addCD(aArtist, "CD2"); //Overwrites arraylist from CD1
aCD.addSong(aArtist, "song2", "2:00");

You use the same Artist object. If you post your addCD method implementation it will be more open for us.