If the String has number inside then square the number and return as a String. How do i replace old number with the squared number Java

Question

So it should work like that

squareDigits("a22b") on "a44b"

squareDigits("a9b2") on "a81b4"

What I have got so far :

public class Code {
    public static void main(String[] args) {
        String ok = "a2b9";
        System.out.println(squareDigits(ok)); // "a81b4"
    }

  public static String squareDigits(String s) {
        char[] pena = s.toCharArray();
        int aboba;
        for (char c : pena) {
            if (Character.isDigit(c)) {
                String s1 = Character.toString(c);
                int b = Integer.parseInt(s1);
                aboba = b * b;
                System.out.println(aboba);
            }
        }
        return "";
        }
    }

Im only beginner and this would very help me out

Answer 1

try as well.

public static void main(String[] args) {
    String ok = "a2b9";
    System.out.println(squareDigits(ok)); // "a81b4"
}

public static String squareDigits(String s) {
    StringBuilder sb = new StringBuilder();
    String[] chars = s.split("");
    for (String str : chars){
        if (isNumber(str)){
            int num = Integer.valueOf(str);
            Double square = Math.pow(num, 2);
            sb.append(square.intValue());
        } else {
            sb.append(str);
        }
    }
    return sb.toString();
}

private static boolean isNumber(String str) {
    try {
        Integer.valueOf(str);
        return true;
    } catch (Exception e) {
        return false;
    }
}