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Sorting with JDK 8 Comparator interface
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| import static java.lang.System.out; | |
| import java.util.ArrayList; | |
| import java.util.Comparator; | |
| import java.util.List; | |
| import java.util.stream.Collectors; | |
| public class Main { | |
| private static List<Song> generateSongs() { | |
| final ArrayList<Song> songs = new ArrayList<>(); | |
| songs.add( | |
| new Song( | |
| "Photograph", | |
| "Pyromania", | |
| "Def Leppard", | |
| 1983)); | |
| songs.add( | |
| new Song( | |
| "Hysteria", | |
| "Hysteria", | |
| "Def Leppard", | |
| 1987)); | |
| songs.add( | |
| new Song( | |
| "Shout", | |
| "Songs from the Big Chair", | |
| "Tears for Fears", | |
| 1984)); | |
| songs.add( | |
| new Song( | |
| "Everybody Wants to Rule the World", | |
| "Songs from the Big Chair", | |
| "Tears for Fears", | |
| 1985)); | |
| songs.add( | |
| new Song( | |
| "Head Over Heels", | |
| "Songs from the Big Chair", | |
| "Tears for Fears", | |
| 1985 | |
| )); | |
| songs.add( | |
| new Song( | |
| "Enter Sandman", | |
| "Metallica", | |
| "Metallica", | |
| 1991 | |
| ) | |
| ); | |
| songs.add( | |
| new Song( | |
| "Money for Nothing", | |
| "Brothers in Arms", | |
| "Dire Straits", | |
| 1985 | |
| ) | |
| ); | |
| songs.add( | |
| new Song( | |
| "Don't You (Forget About Me)", | |
| "A Brass Band in African Chimes", | |
| "Simple Minds", | |
| 1985 | |
| ) | |
| ); | |
| return songs; | |
| } | |
| /** | |
| * Returns a sorted version of the provided List of Songs that is | |
| * sorted first by year of song's release, then sorted by artist, | |
| * and then sorted by album. | |
| * | |
| * @param songsToSort Songs to be sorted. | |
| * @return Songs sorted, in this order, by year, artist, and album. | |
| */ | |
| private static List<Song> sortedSongsByYearArtistAlbum( | |
| final List<Song> songsToSort) { | |
| return songsToSort.stream() | |
| .sorted( | |
| Comparator.comparingInt(Song::getYear) | |
| .thenComparing(Song::getArtist) | |
| .thenComparing(Song::getAlbum)) | |
| .collect(Collectors.toList()); | |
| } | |
| public static void main(final String[] arguments) { | |
| final List<Song> songs = generateSongs(); | |
| final List<Song> sortedSongs = sortedSongsByYearArtistAlbum(songs); | |
| out.println("Original Songs:"); | |
| songs.stream().forEach(song -> out.println("\t" + song)); | |
| out.println("Sorted Songs"); | |
| sortedSongs.forEach(song -> out.println("\t" + song)); | |
| } | |
| } |
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| public class Song { | |
| private final String title; | |
| private final String album; | |
| private final String artist; | |
| private final int year; | |
| public Song(final String newTitle, final String newAlbum, | |
| final String newArtist, final int newYear) { | |
| title = newTitle; | |
| album = newAlbum; | |
| artist = newArtist; | |
| year = newYear; | |
| } | |
| public String getTitle() | |
| { | |
| return title; | |
| } | |
| public String getAlbum() | |
| { | |
| return album; | |
| } | |
| public String getArtist() | |
| { | |
| return artist; | |
| } | |
| public int getYear() | |
| { | |
| return year; | |
| } | |
| @Override | |
| public String toString() { | |
| return "'" + title + "' (" + year + ") from '" + album + "' by " + artist; | |
| } | |
| } |
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