How To Get Free Disk Space In Java

In Java old days, it lacks of method to determine the free disk space on a partition. But this is changed since JDK 1.6 released, a few new methods – getTotalSpace(), getUsableSpace() and getFreeSpace(), are bundled with java.io.File to retrieve the partition or disk space detail.

Example

package com.ashish;
 
import java.io.File;
 
public class DiskSpaceDetail
{
    public static void main(String[] args)
    { 
     File file = new File("c:");
     long totalSpace = file.getTotalSpace(); //total disk space in bytes.
     long usableSpace = file.getUsableSpace(); ///unallocated / free disk space in bytes.
     long freeSpace = file.getFreeSpace(); //unallocated / free disk space in bytes.
 
     System.out.println(" === Partition Detail ===");
 
     System.out.println(" === bytes ===");
     System.out.println("Total size : " + totalSpace + " bytes");
     System.out.println("Space free : " + usableSpace + " bytes");
     System.out.println("Space free : " + freeSpace + " bytes");
 
     System.out.println(" === mega bytes ===");
     System.out.println("Total size : " + totalSpace /1024 /1024 + " mb");
     System.out.println("Space free : " + usableSpace /1024 /1024 + " mb");
     System.out.println("Space free : " + freeSpace /1024 /1024 + " mb");
    }
}

Output

Display the disk space detail in c: partition.

 === Partition Detail ===
 
 === bytes ===
Total size : 52428795904 bytes
Space free : 33677811712 bytes
Space free : 33677811712 bytes
 === mega bytes ===
Total size : 49999 mb
Space free : 32117 mb
Space free : 32117 mb

Note
Both getFreeSpace() and getUsableSpace() methods are return the same total free disk space of a given partition. But the real different is not clear, even in the java doc. Tell me if you know what’s the different in between.