How to alter a character in a string in java

Question

Scanner s=new Scanner(System.in);
String str=s.nextLine();
str.charAt(2)='a';

I have used substr function . but can it be done without it? Why is this statement incorrect?

Answer 1

Strings are immutable in JAVA. You can convert it to a Character Array and then alter the characters.

String str = s.nextLine();
char[] chrArray = str.toCharArray();
chrArray[2] = 'a';

If you want a String out of it then you can do:

String finalStr = new String(chrArray);

Answer 2

You can use setCharAt like this:

  StringBuilder string = new StringBuilder(str);
    string.setCharAt(2, 'a');

Or char[] array:

  char[] nameChars = str.toCharArray();
  nameChars[2] = 'a';

Answer 3

StringBuilder sb =new StringBuilder(str);
    System.out.println(" string is : "+sb.replace(2, 3, "a"));

sb.replace(start index,endindex,replace string)
start index ;- string start index
end index ;- end index for example if you want to replace single char then start 2 and end 3