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<String> summaryRanges(int[] nums) {         List<String> ans = new ArrayList<String>();    if(nums==null){        return ans;    }    int len =0;    StringBuilder temp = null;    for(int i=0; i<(len=nums.length);++i){        int k = nums[i];        temp = new StringBuilder();        temp.append(nums[i]);        while(i+1<len && nums[i+1] == nums[i]+1){            ++i;        }        if(nums[i]!=k){            temp.append("->");            temp.append(nums[i]);        }        ans.add(temp.toString());    }    return ans;    }}