public class DigitsStringCheck { public boolean hasDigitsOnly(String str) { if (str == null || str.length() == 0) return false; for (int i = 0; i < str.length(); i++) if (str.charAt(i) < '0' || str.charAt(i) > '9') return false; return true; } public static void main(String[] args) { DigitsStringCheck dsc = new DigitsStringCheck(); String str1 = "1234567"; String str2 = "43sf334235"; System.out.println("Does " + str1 + " have digits only? " + dsc.hasDigitsOnly(str1)); System.out.println("Does " + str2 + " have digits only? " + dsc.hasDigitsOnly(str2)); } }