Array:Summary Ranges

Given a sorted integer array without duplicates, return the summary of its ranges.
For example, given [0,1,2,4,5,7], return ["0->2","4->5","7"].

public class Solution {
    public List summaryRanges(int[] nums) {
       List list = new ArrayList();
        if (nums.length==1) {
            list.add(nums[0]+"");
            return list;
        }
        for (int i = 0; i < nums.length; i++) {
            int start = nums[i];
            while (i+1"+nums[i]);
            } else {
                list.add(start+"");
            }
        }
        return list;
    }
}