如何将一个整数限制为3位

Question

I am wondering if anyone knows how I could limit an integer to 3 digits. If the number is shorter than 3 digits, I want to output a number prepended with zeroes. If the number is longer than 3 digits, I want to output only the leading three digits.

For example:

• If a "long" number such as 382198 is inputted, the expected output would be 382 .
• If a "short" number such as 62 is inputted, the expected output would be 062 .
• If a number with exactly 3 digits such as 123 is inputted, the expected output would be 123 .

I have tried using DecimalFormat and StringFormat, but I did not have any success with either. I would like to avoid creating any extra objects if possible.

Thanks!

Answer 1

You can do something like this:

 public class DigitsFormatter {
    public static void main(String[] args) {
        System.out.println(limitDigits(123232)); //123
        System.out.println(limitDigits(12)); //012
    }

    public static String limitDigits(int n) {
        String str = String.valueOf(n);
        if (str.length() > 3) {
            str = str.substring(0,3);
        }
        return String.format("%03d", Integer.valueOf(str));
    }
}

Answer 2

This example code shows how to use '/' and System.out.printf to obtain what you want without expensive Objects being created

    int val = 99;
    while (val > 1000) 
        val = val / 10;

    System.out.printf("%03d%n", val);

    val = 123456;
    while (val > 1000) 
        val = val / 10;

    System.out.printf("%03d%n", val);