wanting 2nd octet of an IP address

I don't know enough java, so I am probably doing this wrong. What I would like to have, is a String that has the second octet of an IP address, weather it is an 8 or 58 or 103, just as an example.

Code :

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import java.net.*;
import java.io.*;
import javax.swing.JOptionPane;
public class findip {
public static void main(String [] args) throws IOException{
	String myip,myip2;
	InetAddress thisIp =InetAddress.getLocalHost();
	//System.out.println("IP of my system is := "+thisIp.getHostAddress());
	myip=thisIp.getHostAddress();
	myip2=myip.charAt(3)+myip.charAt(4);
	//need to just show or have 2nd octet
	JOptionPane.showMessageDialog(null,"IP:__"+myip+"\n\nSchool Num:__"+myip2);
}}

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It's not an octet. It's decimal. This example here shows the last part of an IP. You can modify it to get the 1st, 2nd or 3rd part.
1st: myIP.substring(0, myIP.indexOf(".");
2nd: myIP.substring(myIP.indexOf(".")+1, myIP.indexOf(".", myIP.indexOf(".")+1));
etc.

Code java:

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import javax.swing.JOptionPane;
import java.net.InetAddress;
public class WhatIP {
	public static void main(String[] args) {
		try {
			InetAddress ia = InetAddress.getByName(args[0]);
			String myIP = ia.toString();
			JOptionPane.showMessageDialog( null, myIP+"last Part = "+myIP.substring(myIP.lastIndexOf('.')+q, myIP.length())); 
		} catch (Exception e) {
			e.printStackTrace();
		}
  	}
}

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