As mentioned in the comments you cannot do that.
However, you could check if the user's input is an integer and also less than a certain amount of characters and if not prompt them to try again:
import java.util.Scanner;
public class Main {
private static int getIntInputBelowCertainLength(String prompt, Scanner scanner, int maxLength) {
int validInteger = -1;
System.out.print(prompt);
while (scanner.hasNext()) {
if (scanner.hasNextInt()) {
validInteger = scanner.nextInt();
if (String.valueOf(validInteger).length() <= maxLength) {
break;
} else {
System.out.println("ERROR: Input integer was too long, try again...");
System.out.print(prompt);
}
} else {
System.out.println("Error: Invalid input, must be an integer, try again...");
System.out.print(prompt);
scanner.next();
}
}
return validInteger;
}
public static void main(String[] args) {
try (Scanner scanner = new Scanner(System.in)) {
int maxLength = 4;
String prompt = String.format("Enter an integer with less than %d digits: ", maxLength);
int num = getIntInputBelowCertainLength(prompt, scanner, maxLength);
System.out.printf("Valid input! You entered: %d, an integer less than or equal to %s characters long%n",
num, maxLength);
}
}
}
Example Usage:
Enter an integer with less than 4 digits: a
Error: Invalid input, must be an integer, try again...
Enter an integer with less than 4 digits:
