Given a collection of intervals, merge all overlapping intervals.

MergeIntervals.java

/*
Given a collection of intervals, merge all overlapping intervals.

Example 1:

Input: [[1,3],[2,6],[8,10],[15,18]]
Output: [[1,6],[8,10],[15,18]]
Explanation: Since intervals [1,3] and [2,6] overlaps, merge them into [1,6].
Example 2:

Input: [[1,4],[4,5]]
Output: [[1,5]]
Explanation: Intervals [1,4] and [4,5] are considered overlapping.
*/    

public List<Interval> merge(List<Interval> intervals) {
         int currentIndex = 0, iteratorIndex = 1;
        while (iteratorIndex < intervals.size() && currentIndex < intervals.size()){

            Interval current = intervals.get(currentIndex);
            Interval next = intervals.get(iteratorIndex);

            if (current.end >= next.start && current.start <= next.end && iteratorIndex != currentIndex) {
                intervals.get(currentIndex).end = current.end < next.end ? next.end : current.end;
                intervals.get(currentIndex).start = current.start < next.start ? current.start : next.start;
                intervals.remove(next);
                iteratorIndex = currentIndex;
            } else {
                iteratorIndex++;
            }

            if (iteratorIndex == intervals.size()) {
                iteratorIndex = currentIndex;
                currentIndex++;
            }
            if (currentIndex == intervals.size()) {
                iteratorIndex++;
                currentIndex = 0;
            }
        }
        return intervals;
    }

This solution has "Time Limit Exceeded" error for large inputs.
@farsialgorithm
could you help me to improve this snippet code.

Success

Runtime: 7 ms, faster than 94.57% of Java online submissions for Merge Intervals.
Memory Usage: 39.2 MB, less than 97.89% of Java online submissions for Merge Intervals.