Android : Can I make 2 directories with one line of code?

Is it possible to make 2 directories with java?

example:

File dir = new File("/mnt/sdcard/Download/a/b");

Will both directories a and b be created with this code?

Or should I first create directory a and then create b

example:

File dira = new File("/mnt/sdcard/Download/a");
File dirb = new File("/mnt/sdcard/Download/a/b");