no response on java call to windows command in oracle

I trying to get free space on my database disk. I had test of many ways without success. This is the last i tried. I create a JAVA SOURCE in oracle which invokes Runtime.getRuntime().exec() in java. The code is:

CREATE OR REPLACE AND RESOLVE JAVA SOURCE NAMED TEST.DISKS_FREE as 
      import java.io.IOException;
      import java.io.InputStreamReader;
      import java.io.BufferedReader;

      public class diskfreespace
      {
       public static String loaddisk() throws IOException,InterruptedException
       {
       //Process p=Runtime.getRuntime().exec("cmd.exe /c wmic /node:\"%COMPUTERNAME%\" LogicalDisk Where DriveType=\"3\" Get DeviceID,FreeSpace|find /I \":\""); 
       Process p=Runtime.getRuntime().exec("cmd.exe /c dir|find \"bytes free\"");  
       //Process p=Runtime.getRuntime().exec("cmd /c dir");
              //p.waitFor(); 
                BufferedReader reader=new BufferedReader(
                    new InputStreamReader(p.getInputStream())
                ); 
                String line; 
                String result ="";
                while((line = reader.readLine()) != null) 
                { 
                    result+="\n"+line;
                }  
       return result;
      }
    }

As you can see, this method call to command cmd.exe /c dir|find "bytes free". In java environment, this code works perfectly, returning C: 13741621248, but in oracle it never send a response. I tried with other command cmd /c dir list directories for both cases.

Any idea? Regards.