package nodomain.freeyourgadget.gadgetbridge.model;

public class MusicSpec {
    public static final int MUSIC_UNDEFINED = 0;
    public static final int MUSIC_PLAY = 1;
    public static final int MUSIC_PAUSE = 2;
    public static final int MUSIC_PLAYPAUSE = 3;
    public static final int MUSIC_NEXT = 4;
    public static final int MUSIC_PREVIOUS = 5;

    public String artist = "";
    public String album = "";
    public String track = "";
    public int duration;
    public int trackCount;
    public int trackNr;

    @Override
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof MusicSpec)) {
            return false;
        }
        MusicSpec musicSpec = (MusicSpec) obj;

        return this.artist.equals(musicSpec.artist) &&
                this.album.equals(musicSpec.album) &&
                this.track.equals(musicSpec.track) &&
                this.duration == musicSpec.duration &&
                this.trackCount == musicSpec.trackCount &&
                this.trackNr == musicSpec.trackNr;

    }
}

package nodomain.freeyourgadget.gadgetbridge.model;

import java.util.Objects;

public class MusicSpec {
    public static final int MUSIC_UNDEFINED = 0;
    public static final int MUSIC_PLAY = 1;
    public static final int MUSIC_PAUSE = 2;
    public static final int MUSIC_PLAYPAUSE = 3;
    public static final int MUSIC_NEXT = 4;
    public static final int MUSIC_PREVIOUS = 5;

    public String artist;
    public String album;
    public String track;
    public int duration;
    public int trackCount;
    public int trackNr;

    @Override
    public boolean equals(Object obj) {
        if (obj == this) {
            return true;
        }
        if (!(obj instanceof MusicSpec)) {
            return false;
        }
        MusicSpec musicSpec = (MusicSpec) obj;

        return Objects.equals(this.artist, musicSpec.artist) &&
                Objects.equals(this.album, musicSpec.album) &&
                Objects.equals(this.track, musicSpec.track) &&
                this.duration == musicSpec.duration &&
                this.trackCount == musicSpec.trackCount &&
                this.trackNr == musicSpec.trackNr;

    }
}

fix NPE by using Objects.equals()