Java Multi-Level Comparator

Question

I am working on a problem where I must take these \"Song-artist pairs\" from an input file and sort alphabetically. The guidelines to the sorting goes like so:

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Answer 1

In your compare method, compare the song titles if the artists names are identical. Like this:

public static class SongComparator implements Comparator<Song>{
    public int compare(Song a, Song b){
        int rslt a.effectiveAuthor().compareTo(b.effectiveAuthor());
        if (rslt ==0)
        {
            // compare song names
            rslt = a.getSongName().compareTo(b.getSongName());
        }
        return rslt;
    }
}

Answer 2

Let's say the class you said you managed to create is called SongArtistPair and it has a method called effectiveAuthor()which returns the author's name without the The, and a method getSongName() which returns the name of the song. You can use this pattern offered by the Java 8 Comparator API.

Comparator<SongArtistPair> comp = Comparator.comparing(SongArtistPair::effectiveAuthor).thenComparing(SongArtistPair::getSongName);

After that, just use that comp as normal

Check Comparator API docs for more cool stuff HERE