Changing Certain Chars in A String

Question

I'm a beginner programmer and I'm trying to make a very simple version of Hangman. I'm having so problem with my code. This is the portion of code I'm having a problem with:

        for(int i = 0; i <= wordLength - 1; i++ ) {

            if (letter == theWord.charAt( i )) {

                onemore=i+1;
                System.out.println("This letter matches with letter number " + onemore + " in the word.");
                ***displayWord.charAt(i)=letter;***
                System.out.println("The word so far is " + displayWord);
            } 

        }

The part I'm getting an error with has 3 asterisks on either side of it.

displayWord is a String and letter is a char.

Netbeans tells me:

unexpected type
  required: variable
  found:    value

I have no idea what the problem is.

Answer 1

Basically, Java Strings are immutable, that is, there contents can't be changed.

You'd be better of using a StringBuilder.

String theWord = "This is a simple test";
char letter = 'i';
char changeTo = '-';

StringBuilder displayWord = new StringBuilder(theWord);

int i = theWord.indexOf(letter);
if (i != -1) {
    System.out.println("This letter matches with letter number " + (i + 1) + " in the word.");
    displayWord.setCharAt(i, changeTo);

    System.out.println("The word so far is " + displayWord);
}

System.out.println(displayWord);

This results in:

This letter matches with letter number 3 in the word.
The word so far is Th-s is a simple test
This letter matches with letter number 6 in the word.
The word so far is Th-s -s a simple test
This letter matches with letter number 12 in the word.
The word so far is Th-s -s a s-mple test
Th-s -s a s-mple test

Now the short version might look something like

String displayWord = theWord.repace(letter, changeTo);