public static void main(String[] args) {
System.out.println("Please enter an eight-digit string:");
Scanner scanner = new Scanner(System.in);
String str = scanner.nextLine();
//Determine whether the string is eight digits
if(str.length() != 8){
System.out.println("String is not eight digits");
return;
}
char [] c =str.toCharArray();
for (char c1 : c) {
//Determine whether c is an alphabetic character , the front LowerCase is lowercase, and the back UpperCase is uppercase, it returns True, otherwise it returns False
if(!Character.isLowerCase(c1) && !Character.isUpperCase(c1)){
System.out.println("String contains non-alphabetic characters!");
return;
}
}
}