IP subnet Address - Java Network

Java examples for Network:IP Address

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Description

IP subnet Address

Demo Code


//package com.java2s;
import java.net.InetAddress;
import java.net.UnknownHostException;

public class Main {
    public static InetAddress subnetAddress(InetAddress address,
            int networkPrefixLength) throws IllegalArgumentException {
        byte[] rawAddress = address.getAddress();
        byte[] newRawAddress = new byte[rawAddress.length];

        int count = 0;
        for (int i = 0; i < rawAddress.length; i++) {
            byte octet = 0x00;

            if (count < networkPrefixLength) {
                int value;

                for (int bit = 7; bit >= 0; bit--) {
                    value = 0x00;/* www  . ja v a  2  s  . c  o  m*/
                    if (count < networkPrefixLength) {
                        value = ((rawAddress[i] >>> bit) & 0x01);
                    }

                    octet |= ((value & 0x01) << bit);
                    count++;
                }
            }
            newRawAddress[i] = octet;
        }

        try {
            return InetAddress.getByAddress(newRawAddress);
        } catch (UnknownHostException e) {
            throw new IllegalArgumentException(
                    "Internet Address must contain either 4 or 16 octets!");
        }
    }
}

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