如何更改子字符串的值？

Question

我正在尝试制作一个经典的hangman程序(GUI很好,没问题),用户一次猜出一个字母.问题是,当用户猜到一个字母时,它会用猜到的字母替换"_"的位置(如果字母在单词中),但是当猜到下一个字母时,它会忘记最后一个猜测,并且地方回到"_".对不起,如果不清楚,这是一个例子

Word is tiger,  
user guesses "g",  
outputs _ _ g _ _,  
user guesses "r",  
outputs _ _ _ _ r.

我希望代码如何工作:

Word is tiger,  
user guesses "g",  
outputs _ _ g _ _,  
user guesses "r",  
outputs _ _ g _ r.

我怎样才能做到这一点？请记住,老虎只是一个例子,单词是从数组中随机抽取的.我认为唯一的方法是在空格中更改子字符串的值,但我不知道如何做到这一点.截至目前,用户猜出GUI窗口中的字母(男人本人所在的位置)并通过按下按钮提交答案.输出现在只打印在控制台上.

这是该计划的麻烦部分:

// guess is the name of JTextPane next to button
// randWord is the word pulled randomly from an array
private void guessLetter() {
    guessedLetter = guess.getText();
    if (randWord.contains(guessedLetter)){
        reveal(); // method below
    } else {
        wrongGuesses++; // when wrongGuesses adds,
        update(); // another body part is added, method not below
    }
}

private void reveal() {
    int start = randWord.indexOf(guessedLetter); //gets the index of the letter guessed
    String print = blanks.substring(0, start) + guessedLetter + blanks.substring(start+1); //reveals the letter
    System.out.println(print);//prints the revealed letter in correct spot
}

Answer 1

解决这个问题的一种方法是维护一个StringBuilder在每次猜测字母时都会更新的对象.

String wordToGuess = "tiger";
StringBuilder wordToShow = new StringBuilder();
for (int i=0; i < wordToGuess.length(); ++i) {
    wordToShow.append("_");
}

// update publicly shown string; return true if one or more matches found,
// otherwise return false
public boolean guessLetter(char letter) {
    boolean result = false;
    for (int i=0; i < wordToGuess.length(); ++i) {
        if (wordToGuess.charAt(i) == letter) {
            // reveal the correctly guessed character
            wordToShow.setCharAt(i, letter);
            result = true;
        }
    }

    return result;
}

public String reveal() {
    return wordToShow.toString();
}