Merge Intervals

public class Solution {
    public ArrayList<Interval> merge(ArrayList<Interval> intervals) {
        // IMPORTANT: Please reset any member data you declared, as
        // the same Solution instance will be reused for each test case.
        ArrayList<Interval> result = new ArrayList<Interval>();
        if(intervals == null || intervals.size() == 0)
            return result;
            
        Comparator<Interval> comparator = new Comparator<Interval>() {
            public int compare(Interval i1, Interval i2) {
                if (i1.start < i2.start)
                    return -1;
                else if (i1.start > i2.start)
                    return 1;
                else {
                    if (i1.end < i2.end)
                        return -1;
                    else if (i1.end > i2.end)
                        return 1;
                    else
                        return 0;
                }
            }
        };
    Collections.sort(intervals, comparator);
        Interval newinterval = new Interval(intervals.get(0).start, intervals.get(0).end);
        
        for(int i = 1; i < intervals.size(); i++){
            Interval tmp = intervals.get(i);
            if(newinterval.end < tmp.start){
                result.add(newinterval);
                newinterval = new Interval(tmp.start, tmp.end);
            }
            else{
                newinterval.end = Math.max(newinterval.end, tmp.end);
            }
        }
        result.add(newinterval);
        return result;
    }
    
}