In this tutorial, we will write a java program to convert a octal number into binary using while loop. Before that, you must have knowledge of the following topics in C++.

**Binary number**

The binary numbers are based on 0 and 1, so it is a base 2 number. They are the combination of 0 and 1. For example, 1001, 110101, etc.

**Octal number**

The octal numbers are the numbers with base 8 and use the digits 0 to 7. Example: 8 in decimal is represented as 10 in octal, 25 as 31, and so on.

Let us go through a program for the Ocatal to Binary Conversion in java.

**Java Program to Convert Octal number to Binary Number**

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | import java.util.Scanner; public class Main { public static void main(String args[]) { int octalNum, rem, i = 0; int bin = 0, deciNum = 0; Scanner sc = new Scanner(System.in); System.out.print("Enter a Octal Number: "); octalNum = sc.nextInt(); while (octalNum != 0) { deciNum += (octalNum % 10) *Math.pow(8, i); ++i; octalNum /= 10; } i = 1; while (deciNum != 0) { bin += (deciNum % 2) *i; deciNum = deciNum / 2; i *= 10; } System.out.print("Equivalent Binary Value: " + bin); } } |

**Output:**

`Enter a Octal Number: 12`

Equivalent Binary Value: 1010