How to check if a String is numeric in Java

Question

How would you check if a String was a number before parsing it?

Answer 1

// please check below code

public static boolean isDigitsOnly(CharSequence str) {
    final int len = str.length();
    for (int i = 0; i < len; i++) {
        if (!Character.isDigit(str.charAt(i))) {
            return false;
        }
    }
    return true;
}