Code example for Delayed

    public int compareTo(Delayed other) {
        if (other instanceof SkillXpGain) {
            // Use more efficient method if possible (private fields) 
            return this.compareTo((SkillXpGain) other);
        } 
        return (int) (getDelay(TimeUnit.MILLISECONDS) - other.getDelay(TimeUnit.MILLISECONDS));
    } 
 
    @Override 
    public long getDelay(TimeUnit arg0) {
        return arg0.convert(expiryTime - System.currentTimeMillis(), TimeUnit.MILLISECONDS);
    } 
}