Longest Consecutive Sequence hashset

public class Solution {

    public int longestConsecutive(int[] num) {
        HashSet<Integer> hash=new HashSet<Integer>();
        int max=1;
        for(int n:num)
        {
            hash.add(n);
        }
        int j=0;
        while(!hash.isEmpty()&&j<num.length)
        {
           // if(!hash.contains(num[j])) continue;
            int count=1;

            int k=num[j]+1;
            while(hash.contains(k))
            {
                hash.remove(k);
              k=k+1;
                count++;

            }
            k=num[j]-1;
            while(hash.contains(k))
            {
                hash.remove(k);
                k=k-1;
                count++;
            }
             hash.remove(num[j]);

            if(count>max) max=count;
            j++;

         }

            return max;

    }
}

http://www.programcreek.com/2013/01/leetcode-longest-consecutive-sequence-java/