217. Contains Duplicate -with java- (leetcode.com)

Solution.java

/*
Your runtime beats 79.51 % of java submissions.
Your memory usage beats 69.24 % of java submissions.
*/

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