hexaToOcta.java

import java.util.Scanner;

public class Exercise30 {
    public static int hex_to_decimal(String s) {
        String digits = "0123456789ABCDEF";
        s = s.toUpperCase();
        int val = 0;
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            int d = digits.indexOf(c);
            val = 16 * val + d;
        }
        return val;
    }

    public static void main(String args[]) {
        String hexdec_num;
        int dec_num, i = 1, j;
        int octal_num[] = new int[100];
        Scanner in = new Scanner(System.in);

        System.out.print("Input a hexadecimal number: ");
        hexdec_num = in.nextLine();

        // Convert hexadecimal to decimal

        dec_num = hex_to_decimal(hexdec_num);

        // Convert decimal to octal

        while (dec_num != 0) {
            octal_num[i++] = dec_num % 8;
            dec_num = dec_num / 8;
        }

        System.out.print("Equivalent of octal number is: ");
        for (j = i - 1; j > 0; j--) {
            System.out.print(octal_num[j]);
        }
        System.out.print("\n");
    }
}