Decimal to Octal and Hexadecimal

/*
 * Problem : Convert a decimal number to octal and hexadecimal.
 * Input   : One non-negative integer.
 * Output  : Two lines: Octal and Hexadecimal.
 * Approach: Divide by the base and use a table of digit characters.
 * Time    : O(log n)
 * Space   : O(log n)
 * Java    : 8 or newer.
 */
import java.util.Scanner;

public class Main {
    // This method receives a number and a base (8 or 16). It returns the number written in that base.
    static String convert(long number, int base) {
        // Step 1: A table of all digit characters. The index in the table is the value of the digit.
        String digits = "0123456789ABCDEF";

        // Step 2: Zero is written as 0.
        if (number == 0) {
            return "0";
        }

        // Step 3: Collect the digits. We get them from the last digit to the first digit.
        StringBuilder result = new StringBuilder();
        while (number > 0) {
            // Step 4: The remainder is the next digit. Look up the character in the table. Example: 255 % 16 = 15 -> 'F'.
            result.append(digits.charAt((int) (number % base)));

            // Step 5: Divide by the base to go to the next digit. Example: 255 / 16 = 15.
            number = number / base;
        }

        // Step 6: Reverse the digits to get the correct order.
        return result.reverse().toString();
    }

    public static void main(String[] args) {
        long number = new Scanner(System.in).nextLong();
        System.out.println("Octal: " + convert(number, 8));
        System.out.println("Hexadecimal: " + convert(number, 16));
    }
}