How can I set a specific positon in a String in Java?

Question

I have a String with name str.

str = "hi john";

Now I want to set j char to g. How can I do that?

Answer 1

You can't modify a String directly, but you can either use a StringBuilder:

str = "hi john";
StringBuilder sb = new StringBuilder(str);
sb.setCharAt(3,'g');
str = sb.toString();    

.. or convert it to a char[] and back

str = "hi john";
char[] chars = str.toCharArray();
chars[3] = 'g';
str = new String(chars);