Character

The type to use for a char that might be null is Character.

void main() {
Character c = null;
IO.println(c);
c = '%';
IO.println(c);
}

Unlike a char[], a Character[] will not have its contents shown when printed.

void main() {
char[] c1 = new char[] { 'a', 'b', 'c' };
IO.println(c1);

Character[] c2 = new Character[] { 'a', 'b', 'c' };
IO.println(c2);
}