Any Java programmers here-need help

For those who've programmed in java, you know that a variable must be initialised in order for it to be used. Sometimes you'll need to initialise a variable to no value.

I can do it for a numerical variable such as an integer.

int x=0;

I can do it for a String variable.

String greeting="";

I need to find out how to set a character variable to a null or space.

Thankyou.