217. Contains Duplicate

public class Solution {
public boolean containsDuplicate(int[] nums) {
HashSet<Integer> hasSet = new HashSet<>();
for (int i = 0; i < nums.length; i++) {
if (hasSet.contains(nums[i]))
return true;
else
hasSet.add(nums[i]);
}
return false;
}
}

Arrays.sort(nums);
for (int i = 0; i < nums.length-1; i++) {
if (nums[i]==nums[i+1]) {
return true;
}
}
return false;