Max Points on a Line leetcode java

 1     public int maxPoints(Point[] points) {  
 2         if(points.length == 0||points == null) 
 3             return 0;  
 4             
 5         if(points.length == 1) 
 6             return 1;  
 7             
 8         int max = 1;  //the final max value, at least one
 9         for(int i = 0; i < points.length; i++) {  
10             HashMap<Float, Integer> hm = new HashMap<Float, Integer>();  
11             int same = 0;
12             int localmax = 1; //the max value of current slope, at least one
13             for(int j = 0; j < points.length; j++) {  
14                 if(i == j) 
15                     continue;  
16                     
17                 if(points[i].x == points[j].x && points[i].y == points[j].y){
18                     same++; 
19                     continue;
20                 }
21                 
22                 float slope = ((float)(points[i].y - points[j].y))/(points[i].x - points[j].x); 
23                 
24                 if(hm.containsKey(slope))  
25                     hm.put(slope, hm.get(slope) + 1);  
26                 else  
27                     hm.put(slope, 2);  //two points form a line
28             }
29             
30             for (Integer value : hm.values())   
31                 localmax = Math.max(localmax, value);  
32           
33             localmax += same;  
34             max = Math.max(max, localmax);  
35         }  
36         return max; 
37     }