public void addChar(char ch) {
        ch = normalize(ch);
        char lastchar = grams_.charAt(grams_.length() - 1);
        if (lastchar == ' ') {
            grams_ = new StringBuffer(" ");
            capitalword_ = false;
            if (ch==' ') return;
        } else if (grams_.length() >= N_GRAM) {
            grams_.deleteCharAt(0);
        }
        grams_.append(ch);

        if (Character.isUpperCase(ch)){
            if (Character.isUpperCase(lastchar)) capitalword_ = true;
        } else {
            capitalword_ = false;
        }
    }