Question

If I don’t know the size of array of chars I’m using, is there a way to use it without setting the size upfront ?

Answer 1

In general, you can use a java.util.List when you don’t know the size up front.

List<Character> chars = new ArrayList<Character>();
chars.add('f');
chars.add('o');
chars.add('o');

Depending on your needs, a StringBuilder might make more sense than a List<Character>.

StringBuilder sb = new StringBuilder();
sb.append('f')
  .append('o')
  .append('o');

If you want to get really slick, use Trove for its list-of-primitives so you can work with the (third-party equivalent of) a List<char>. nevermind. Trove does not have a TCharArrayList.