Question

I’m new to java and i’m trying to find a way of incrementing through an user input IP address range.

For example from 192.168.0.1 to 192.168.0.255. However the way my application works at the moment is the take the from and to ip addresses as a String.

Is there a way I can increment through all the ip addresses the user input from and to?

Hope this makes sense and please dont flame me, I have looked for an answer!

EDIT!

Its actually to ping through the address range so, here’s a little code so far, the ‘host’ is being passed in from another class, which i want to cycle through the addresses:

    public static String stringPing(String stringPing, String host){

    String ipAddress;
    ipAddress = host;

    try
    {
        InetAddress inet = InetAddress.getByName(ipAddress);

        boolean status = inet.isReachable(2000); 

        if (status)
        {
            stringPing = "\n" +host +" is reachable";
            return stringPing;
        }
        else
        {
            stringPing = "\n" +host +" is unreachable";
            return stringPing;
        }
    }
    catch (UnknownHostException e)
    {
        System.err.println("Host does not exists");
    }
    catch (IOException e)
    {
        System.err.println("Error in reaching the Host");
    }

    return stringPing;

}  

Answer 1

Hold address as it should be — as 32-bit integer, and increment it in this form. Convert it from or to String only if required. Example is below. My IPAddress class is complete and functional.

class IPAddress {

    private final int value;

    public IPAddress(int value) {
        this.value = value;
    }

    public IPAddress(String stringValue) {
        String[] parts = stringValue.split("\\.");
        if( parts.length != 4 ) {
            throw new IllegalArgumentException();
        }
        value = 
                (Integer.parseInt(parts[0], 10) << (8*3)) & 0xFF000000 | 
                (Integer.parseInt(parts[1], 10) << (8*2)) & 0x00FF0000 |
                (Integer.parseInt(parts[2], 10) << (8*1)) & 0x0000FF00 |
                (Integer.parseInt(parts[3], 10) << (8*0)) & 0x000000FF;
    }

    public int getOctet(int i) {

        if( i<0 || i>=4 ) throw new IndexOutOfBoundsException();

        return (value >> (i*8)) & 0x000000FF;
    }

    public String toString() {
        StringBuilder sb = new StringBuilder();

        for(int i=3; i>=0; --i) {
            sb.append(getOctet(i));
            if( i!= 0) sb.append(".");
        }

        return sb.toString();

    }

    @Override
    public boolean equals(Object obj) {
        if( obj instanceof IPAddress ) {
            return value==((IPAddress)obj).value;
        }
        return false;
    }

    @Override
    public int hashCode() {
        return value;
    }

    public int getValue() {
        return value;
    }

    public IPAddress next() {
        return new IPAddress(value+1);
    }


}

public class App13792784 {

    /**
     * @param args
     */
    public static void main(String[] args) {


        IPAddress ip1 = new IPAddress("192.168.0.1");

        System.out.println("ip1 = " + ip1);

        IPAddress ip2 = new IPAddress("192.168.0.255");

        System.out.println("ip2 = " + ip2);

        System.out.println("Looping:");

        do {

            ip1 = ip1.next();

            System.out.println(ip1);

        } while(!ip1.equals(ip2));


    }

}