setCharAt not working with string but working with stringbuffer in JAVA why?

Question

public class String2 {
    public static String alterstring(String s) {
        int n = s.length();
        for (int i = 0; i < n; i++) {
            if (s.charAt(i) != 'a' && s.charAt(i) != 'e' && s.charAt(i) != 'i' && s.charAt(i) != 'o' && s.charAt(i) != 'u') {
                int a = s.charAt(i);
                char ch = (char)(a + 1);
                s.setCharAt(i, ch);
            }
        }
        return s;
    }
    public static void main(String[] args) {
        String t;
        String s = new String();
        Scanner input = new Scanner(System.in);
        System.out.println("Enter a string:");
        String s = sc.nextLine();
        t = alterstring(s);
        System.out.println(t);
    }
}

Java `String` is *immutable* (`s = s.setCharAt(i, ch);`), and you should prefer (the newer) `StringBuilder` to `StringBuffer`. Like `Vector` and `ArrayList`, some classes are only kept for compatibility. — Elliott Frisch, Mar 15 '16 at 19:38
still its not working when i use (s = s.setCharAt(i, ch);) and i am using net beans ide. — Shubham, Mar 16 '16 at 17:56

score 0 · Answer 1 · answered Mar 15 '16 at 19:36

0

The setCharAt(...) function doesn't alter the string you are dealing with, it returns a new String with the requested changed character.

answered Mar 15 '16 at 19:36

Edwin Buck

69,361
7
100
138

score 0 · Answer 2 · answered Mar 15 '16 at 19:41

setCharAt not working with string but working with stringbuffer in JAVA why?

It is because setCharAt is a method from the StringBuilder class.

The String class does not have setCharAt method.

If you want to "set" a String, you have to reassign a new String value (new Sting object) back into the String variable.

setCharAt not working with string but working with stringbuffer in JAVA why?

2 Answers2