Java-Mac和Windows之间的文件getFreeSpace区别

Question

I am trying to get the free space from my NAS, but Mac and Windows return different values. I use java.io.File and the method getFreeSpace.

Mac outcome, which is incorrect :

39.13465499... GB

Windows outcome, which is correct :

4134.864555... GB

My code:

    private static String multiMediaFolder;
    private static long freeDiskSpace;


public static void main(String[] args) {

    if (System.getProperty("os.name").equals("Mac OS X")){
        multiMediaFolder = "/Volumes/Multimedia/movies/HD";
    } else if (System.getProperty("os.name").substring(0, 7).equals("Windows")){
        multiMediaFolder = "\\\\QNAP\\Multimedia\\movies\\HD";
    }

    freeDiskSpace = new File(multiMediaFolder).getFreeSpace();
    double sizeInGigaByte = (double) freeDiskSpace / 1024 / 1024 / 1024; 

    System.out.println(sizeInGigaByte);
 }

The paths are different, but point at the same folder. Why is the Mac version way different than the Windows version?

Answer 1

I've got my answer. There are two differences, like we saw in my post above me.

Linux returns 4326416688 <- which are kilobytes.

Mac (just like linux) returns 4326416688 <- which are kilobytes too.

Windows returns a bigger number 4429798060032 <- which are bytes.

This explains why the Windows value was correct.

The code that I am going to use now:

private static String multiMediaFolder;
private static long freeDiskSpace;
private static double sizeInGigaByte;


public static void main(String[] args) {

   if (System.getProperty("os.name").equals("Mac OS X")){
       multiMediaFolder = "/Volumes/Multimedia/movies/HD";
       freeDiskSpace = new File(multiMediaFolder).getFreeSpace();
       sizeInGigaByte = (double) freeDiskSpace / 1024 / 1024;
   } else if (System.getProperty("os.name").substring(0, 7).equals("Windows")){
       multiMediaFolder = "\\\\QNAP\\Multimedia\\movies\\HD";
       freeDiskSpace = new File(multiMediaFolder).getFreeSpace();
       sizeInGigaByte = (double) freeDiskSpace / 1024 / 1024 / 1024;
   }

   System.out.println(sizeInGigaByte);
}