LeetCode - Insert Interval

InsertInterval.java

public List<Interval> insert(List<Interval> intervals, Interval newInterval) {
    ArrayList<Interval> ret = new ArrayList<Interval>();
    if(intervals == null || intervals.size() == 0){
        ret.add(newInterval);
        return ret;
    }
    for(int i=0; i<intervals.size(); i++){
        Interval curInterval = intervals.get(i);
        if(curInterval.end < newInterval.start){
            ret.add(curInterval);
        }else if(curInterval.start > newInterval.end){
            ret.add(newInterval);
            newInterval = curInterval;
        }else{
            newInterval.start = Math.min(newInterval.start, curInterval.start);
            newInterval.end = Math.max(newInterval.end, curInterval.end);
        }
    }
    ret.add(newInterval);
    return ret;
}