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

## Octal To Decimal Java Program :

[java]

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;
}

}

[/java]

Output :

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

Happy Learning 🙂