I don't know which version of java  documentation you have but mine says:

<quote_jdk_1.3>
freeMemory

public long freeMemory()

Returns the amount of free  memory in the system. Calling the gc method  may
result in increasing the value returned by freeMemory.

Returns:
an approximation to the total amount of memory currently available for
future allocated objects, measured in bytes.
</quote_jdk_1.3>

But you can use the Runtime class  and use exec to call for example a dos
command and then grab the output
and parse it. Nasty, but AFAIK there is no other way.

pls note that the runtime class  methods do not provide the hard
disk space  of the system, but give info on physical memory available to java
programs for execution.
pls do not post messages until u have complete idea, this cud mislead
newbies..

I got it
Here is the code,
import java.io.*;
import java.util.*;

public class  GetDiscSpace
{
public static void main( String[] str )
{
Runtime rt = Runtime.getRuntime();
String strDiskSpace = null;
Process p = null;
String strOS = System.getProperty( "os.name" );
try
{
if( strOS.equals( "Windows 2000" ))
{
p = rt.exec("cmd.exe /c dir d:\\" );
}
else
{
// Windows xp
p = rt.exec("cmd.exe /c dir d:\\" );
}

InputStream inStream = p.getInputStream();
BufferedReader reader = new BufferedReader( new
InputStreamReader( inStream));
String strTemp;

while( (strTemp = reader.readLine()) != null )
{
strDiskSpace = strTemp;
}

System.out.println( strDiskSpace.trim() );
StringTokenizer sToken = new StringTokenizer(
strDiskSpace.trim() , " " );

if( sToken.hasMoreTokens())
{
System.out.println( "Free Space : " +
sToken.nextToken() );
}

p.destroy();
}
catch( Exception e )
{
System.out.println( e.getMessage());
}
}
}