java 整型相除得到浮点型

 1 public class TestFloatOrDouble {
 2 
 3     public static void main(String[] args) {
 4         Point num1 = new Point(84, 250);
 5         Point num2 = new Point(21, 10);
 6         
 7         float f1 = (num1.y - num2.y) / (num1.x - num2.x);
 8         float f2 = (float) (num1.y - num2.y) / (num1.x - num2.x);
 9         
10         double d1 = (num1.y - num2.y) / (num1.x - num2.x);
11         double d2 = (double)(num1.y - num2.y) / (num1.x - num2.x);
12         
13         System.out.println(f1);
14         System.out.println(f2);
15         
16         System.out.println(d1);
17         System.out.println(d2);
18     }
19 }
20 
21 class Point{
22     int x;
23     int y;
24     
25     public Point(int x,int y){
26         this.x = x;
27         this.y = y;
28     }
29 }

3.0
3.8095238
3.0
3.8095238095238093