max points on a line

public int (Point[] points) {
    if (points == null || points.length == 0)
        return 0;
    int ans = 0;
    for (int i = 0; i < points.length; ++i) {
        HashMap<Float, Integer> map = new HashMap<>();
        int x1 = points[i].x, y1 = points[i].y;
        int same = 0;
        int vertical = 1;
        int horizontal = 1;
        for (int j = i + 1; j < points.length; ++j) {
            int x2 = points[j].x, y2 = points[j].y;
            if (x1 == x2 && y1 == y2) {
                same += 1;
                continue;
            }
            if (x1 == x2) {
                vertical += 1;
                continue;
            }
            if (y1 == y2) {
                horizontal += 1;
                continue;
            }
            float slope = slope(points[i], points[j]);
            if (map.containsKey(slope)) {
                map.put(slope, map.get(slope) + 1);
            } else {
                map.put(slope, 2);
            }
        }
        int localMax = 0;
        for (int val : map.values()) {
            localMax = Math.max(localMax, val);
        }
        localMax = Math.max(localMax, Math.max(vertical, horizontal));
        localMax += same;
        ans = Math.max(localMax, ans);
    }
    return ans;
}

public float slope(Point p1, Point p2) {
    return (p1.y - p2.y) / (float)(p1.x - p2.x);
}