private void processCharacter(char ch, List<String> stack, List<String> parsed) {
        String newOperator = String.valueOf(ch);

        if (stack.size() > 0) {
            while (!stack.isEmpty() && newOperatorHasSameOrLowerPriority(newOperator, stack.get(stack.size() - 1)) ) {
                parsed.add(stack.get(stack.size() - 1));
                stack.remove(stack.size() - 1);
            }
        } 
        stack.add(newOperator);
        
    }