Replacing the parts of a string with a given index position of the actual string Java

Question

I'm just a little short handed on understanding how I can proceed with my code. I'm basically doing a hang-man game and I made a copy of the the actual word. The copy is replaced with blank spaces and I'm wondering how I can replace the blank spaces when the player correctly guesses a word

        while(!gameOver && difficulty.equals("1") || difficulty.equals("3") || difficulty.equals("2")){
            System.out.println(userWord);
            System.out.print("Enter your guess! Make sure it's a singular letter only!: ");
            choice = inputs.nextLine().toLowerCase();
            while(choice.length()==1){ 
                int check1 = lettersGuessed.indexOf(choice);
                if (check1 == -1){
                    //System.out.println("b");
                    lettersGuessed = lettersGuessed+letter;
                    if (word.indexOf(choice) == -1) {
                        mistakes++; //mISTAKES - add on to here
                        System.out.println("You guessed a wrong letter! Keep guessing!");
                        break;
                    }
                    else{
                        System.out.println("You've guessed a right letter!");
                        String jake = word.indexOf(choice);

                        userWord = userWord.replace(userWord,jake);
                        break;

and this is my game loop. in the else statement at the bottom I don't know how I'm suppose to work this out. At the bottom I can get the index position of the player's guess in the actual word.

Answer 1

字符串在Java中是不可变的。您将要构建一个新字符串。

一种方法是：

char characterGuessed = choice.charAt(0);
StringBuilder builder = new StringBuilder();
for(int i = 0; i < word.length(); i++) {
    if(word.charAt(i) == characterGuessed) {
      builder.append(characterGuessed);
    } else {
      builder.append(userWord.charAt(i));
    }
}
userWord = builder.toString();