Also, if you are talking about inserting the character just so you have the commands on separate lines, like:
command one
command two
you can use the PrintWriter class, it has options to write both on the same line (the print() method), or write one command on one line, and then the next on a new line (the println() method).
You would create the object like this:
PrintWriter write = new PrintWriter( new FileOutputStream( "filename.bat" ) );
And simply call:
write.println( "command one" );
write.println( "command two" );
If you want a whole separate line, something like:
command one
command two
Then you could make three calls like:
write.println( "command one" );
write.println();
write.pritnln( "command two" );
Look at the
API for the IO classes, plenty of things there to handle this.