# Java Program to Convert Octal To Binary

Write a Java program to convert octal to binary. In Java, we can use the parseInt with eight as the second argument to convert the octal string to a binary number.

```package Remaining;

public class OctalToBinary1 {

public static void main(String[] args) {

String s1 = "15";
String s2 = "45";
String s3 = "122";

int a = Integer.parseInt(s1, 8);
int b = Integer.parseInt(s2, 8);
int c = Integer.parseInt(s3, 8);

System.out.println(Integer.toBinaryString(a));
System.out.println(Integer.toBinaryString(b));
System.out.println(Integer.toBinaryString(c));
}
}```
``````1101
100101
1010010``````

This Java example accepts the octal string and converts it to binary number using the parseInt method.

```package Remaining;

import java.util.Scanner;

public class OctalToBinary2 {
private static Scanner sc;

public static void main(String[] args) {

sc= new Scanner(System.in);

System.out.print("Please Enter Octal Number =  ");
String octalString = sc.nextLine();

int decimalVal = Integer.parseInt(octalString, 8);
String binaryVal = Integer.toBinaryString(decimalVal);

System.out.println("Octal To Binary Result = " + binaryVal);
}
}```

Java program to convert octal to binary using the for loop. The first for loop converts the octal to decimal and the second loop converts a decimal to binary number.

```package Remaining;

import java.util.Scanner;

public class OctalToBinary3 {
private static Scanner sc;

public static void main(String[] args) {

sc= new Scanner(System.in);

int octalVal = sc.nextInt();

int i, decimalVal = 0;
long binaryVal = 0;

for(i = 0; octalVal != 0; i++)
{
decimalVal = (int) (decimalVal + (octalVal % 10) * Math.pow(8, i));
octalVal= octalVal / 10;
}

for(i = 1; decimalVal != 0; i = i * 10)
{
binaryVal = binaryVal + (decimalVal % 2) * i;
decimalVal = decimalVal / 2;
}

System.out.println("Result = " + binaryVal);
}
}```
``````Please Enter Number =  124
Result = 1010100``````

Java program to convert octal to binary using a while loop.

```package Remaining;

import java.util.Scanner;

public class OctalToBinary4 {
private static Scanner sc;

public static void main(String[] args) {

sc= new Scanner(System.in);

int octalVal = sc.nextInt();

int i, j, decimalVal = 0;
long binaryVal = 0;
i = 0;

while(octalVal != 0)
{
decimalVal = (int) (decimalVal + (octalVal % 10) * Math.pow(8, i++));
octalVal= octalVal / 10;
}
j = 1;
while(decimalVal != 0)
{
binaryVal = binaryVal + (decimalVal % 2) * j;
decimalVal = decimalVal / 2;
j = j * 10;
}

System.out.println("Result    = " + binaryVal);
}
}```
``````Please Enter Number = 97
Result    = 1001111``````