How to detect system drive using JAVA

You can use:

File[] roots = File.listRoots();

to get the list of drives on your system

I don't need to get list of drives.I need to get main drive where windows installed.

try the following code

String systemDrive = System.getProperty("SystemDrive");

see the following link for reference
http://www.bigresource.com/Tracker/Track-vb-NkqegKV5n3/
http://leepoint.net/notes-java/io/30properties_and_preferences/40sysprops/10sysprop.html

Another approach:

System.out.println(System.getProperty("user.home").charAt(0));

Assuming the user home directory is always an the windows drive.

okay when i try

String systemDrive = System.getProperty("SystemDrive");

i get NULL response

and when i try System.out.println(System.getProperty("user.home").charAt(0));

i get the following error

found   : char
required: java.lang.String
        private String drv = System.getProperty("user.home").charAt(0);

but java.lang package is imported already