Поиск букв в строке (java)

реализация на replace

String word = "винЕгред";
String alphabet = "абвгдеёжзийклмнопрстуфхцчшщъыьэюя";
String currWord;
BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
do {
    char letter = reader.readLine().toLowerCase().charAt(0);
    alphabet = alphabet.replace(letter, '*');
    currWord = word;
    for (char ch : alphabet.toCharArray()){
        currWord = currWord.replace(ch, '-');
        currWord = currWord.replace(Character.toUpperCase(ch), '-');
    }
    System.out.println(currWord);
} while (currWord.contains("-"));
reader.close();
System.out.println("вы выиграли!!!");