Here we are going to write a program on conversion of Octal To Decimal Numbers in Java.

Octal To Decimal Java Program :


import java.util.Scanner;

public class ConvertOctalToDecimal {

    public static void main(String[] args) {
        // TODO Auto-generated method stub
        Scanner sc = new Scanner(System.in);
        System.out.println("Enter a Oct Number :");
        String input = sc.nextLine();
        convertOctalToDecimal(input);
    }
    
    public static int convertOctalToDecimal(String octal) {
        int decimal = 0;
        int power = 0;
        if (octal != null && !octal.isEmpty()) {
            if (isOctal(octal)) {
                if (octal.length() > 1) {
                    int number = Integer.parseInt(octal);

                    while (number > 0) {
                        decimal = decimal + (number % 10) * (int) Math.pow(8, power);
                        power++;
                        number /= 10;
                    }
                } else {
                    decimal = Integer.valueOf(octal);
                }
            } else {
                System.out.println("The number is not an octal format");
            }
            System.out.println("The decimal number is: " + decimal);
        }

        return decimal;
    }
    public static boolean isOctal(String octal) {

        boolean isOctal = false;

        if (octal != null && !octal.isEmpty()) {
            int number = Integer.parseInt(octal);

            while (number > 0) {
                if (number % 10 <= 7) {
                    isOctal = true;
                } else {
                    isOctal = false;
                    break;
                }
                number /= 10;
            }
        }

        return isOctal;
    }

}

Output :

Enter a Oct Number :  20
The decimal number is: 16
Oct is : 16

Happy Learning 🙂