public static void main(String[] args) {
        for(File file : File.listRoots()){ // listRoots() method return list of drives. array of File type.
        	search(file);
        }
    }
 
    public static void search(File f) {  
        if ( !f.exists() ) return; 
        String name = f.getName();
        System.out.println(name);
        if ( f.isDirectory() ) {
        File[] files = f.listFiles();
        for( int i = 0 ; i < files.length; i++ ) {
        search( files[i] );
            }
        }
    }