Converting an IP address to binary values (Java)

Question

I'm trying to write a program in Java that will take an IP address and convert to binary.

Here is what I have so far:

import java.util.Scanner;

public class IpConverter{

public static void main (String[]args)
{

    int result;

    String data_in;

    int data_out;

        Scanner scan = new Scanner(System.in);

        try
        {
            System.out.print("Enter an IP address: ");
            data_in = scan.next();

            data_out = Integer.parseInt(data_in, 10);
            System.out.println (data_in + "is equivalent to" + data_out);
        }
        catch (NumberFormatException nfe){
            System.out.println("Wrong data type!");

        }
    }
}

Assuming your ips are being entered in dotted.quad format (eg 127.0.0.1), parseint isn't going to give you a full 32bit representation of that, since that's not a valid int. — Marc B
– Marc B, Commented Mar 28, 2012 at 2:17
For future reference, if you select all of your code and press CTRL+K you will get one big code block instead of the many small ones you originally had. — Jeffrey
– Jeffrey, Commented Mar 28, 2012 at 2:19
There are answers to the same question at stackoverflow.com/questions/1146581/… — Shuo Ran
– Shuo Ran, Commented Mar 28, 2012 at 2:33

Óscar López · Accepted Answer · 2012-03-28 04:06:39Z

7

Building on jtahlborn' answer:

byte[] bytes = InetAddress.getByName(data_in).getAddress();
data_out = new BigInteger(1, bytes).toString(2);

Now data_out contains the IP address as a binary number.

edited Mar 28, 2012 at 4:06

answered Mar 28, 2012 at 2:45

Óscar López

237k38 gold badges321 silver badges391 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

jtahlborn · Accepted Answer · 2012-03-28 02:31:25Z

4

you can use InetAddress to parse the textual representation and convert to a byte[]. you can use BigDecimal to convert a byte[] to a big integer.

answered Mar 28, 2012 at 2:31

jtahlborn

53.8k5 gold badges80 silver badges122 bronze badges

Comments

Dan675 · Accepted Answer · 2012-03-28 02:41:30Z

2

Scanner in = new Scanner(System.in);
System.out.println("Please enter an IP Address.");
String ip = in.nextLine();
String[] octetArray = ip.split("\\.");
for (String string : octetArray){
    int octet = Integer.parseInt(string);
    String binaryOctet = Integer.toBinaryString(octet);
    System.out.println(binaryOctet);
}

so for input 10.10.150.1 output will be

1010

10010110

1

answered Mar 28, 2012 at 2:41

Dan675

1,77715 silver badges15 bronze badges

5 Comments

jerms246 Over a year ago

The string ip = in.nextLine(); command is giving me an error. "error: cannot find symbol String ip = in.nextLine();"

Dan675 Over a year ago

That's weird, the code is copied directly from my code that ran fine.

jerms246 Over a year ago

Anything else i need to import?Other than java.util.Scanner? I also have java.lang.String imported as well.

Dan675 Over a year ago

Scanner is the only think you should need imported.

jerms246 Over a year ago

Not working, man. You think you could add some more of your code to see if I'm missing anything?

Michael Yakobi · Accepted Answer · 2013-10-23 20:24:21Z

0

If you want to avoid name resolution, you can use the following code that converts an IPv4 address string to a byte array:

String[] octetArray = ipAddressStr.split("\\.");
assert octetArray.length == 4;
byte[] ipAddressBytes = new byte[4];
for (int i = 0; i < 4; ++i) {
    ipAddressBytes[i] = Integer.valueOf(octetArray[i]).byteValue();
}

answered Oct 23, 2013 at 20:24

Michael Yakobi

1,1501 gold badge12 silver badges13 bronze badges

Comments

Sean F · Accepted Answer · 2019-02-09 03:35:12Z

The open-source IPAddress Java library can do this for you. It can parse various IP address formats, including either IPv4 or IPv6. Disclaimer: I am the project manager of the IPAddress library.

Here is sample code similar to yours:

public static void main(String[] args) {
    try(Scanner scan = new Scanner(System.in)) {
        System.out.print("Enter IP addresses: ");
        while(true) {
            String data_in = scan.next();
            IPAddressString string = new IPAddressString(data_in);
            IPAddress addr = string.toAddress();
            System.out.println(addr + " is equivalent to " + addr.toBinaryString());
        }
    } catch (AddressStringException e){
        System.out.println("invalid format: " + e.getMessage());
    } catch(NoSuchElementException e) {}
}

Example usage:

Enter IP addresses: 1.2.3.4 a:b:c:d:e:f:a:b
1.2.3.4 is equivalent to 00000001000000100000001100000100
a:b:c:d:e:f:a:b is equivalent to 00000000000010100000000000001011000000000000110000000000000011010000000000001110000000000000111100000000000010100000000000001011

Collectives™ on Stack Overflow

Converting an IP address to binary values (Java)

5 Answers 5

Comments

Comments

5 Comments

Comments

Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

5 Answers 5

Comments

Comments

5 Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related