/**
* Adds a Song to the SongCollection
*
*/
public void addSong(String title, Song song) throws Exception {
Song old = (Song) songMap.put(title, song);
if (old != null) {
System.out.println("SongCollection.addSong: song already exists, not added : " + title);
songMap.put(old.getTitle(), old);
throw new Exception ("Duplicate song title");
}
}