Question

I’m using Collections.sort to sort a ArrayList of objects, and I want to see if there is a more efficient compareTo method for what I’m trying to do.

Here’s the method:

@Override
public int compareTo(Song s) {
    if (runningTime > s.runningTime) {
        return -1;
    } else if (runningTime < s.runningTime) {
        return 1;
    }
    int lastCmp = title.compareTo(s.title);
    return (lastCmp != 0 ? lastCmp : composer.compareTo(s.composer));
}

If anyone could suggest a more efficient method (i.e. quicker runtime) I would be very grateful.

Answer 1

Just like MeBigFatGuy said, any improvement is insignificant, but I think you can still clean up the code a bit to reduce unnecessary if-else condition. My two cents.

public int compareTo(Song s) {
    if (runningTime != s.runningTime) {
        return s.runningTime - runningTime;
    }
    else {
        int lastCmp = title.compareTo(s.title);
        return (lastCmp != 0 ? lastCmp : composer.compareTo(s.composer));
    }
}