How do i check a ip address range whether it falls in Class A Class B Class C

Question

import java.net.*;
import java.io.*;

public class ip_host {
    public static void main(String args[]) throws Exception {
        System.out.println("Enter the host name :");
        String n = new DataInputStream(System.in).readLine();

        InetAddress ipadd = InetAddress.getByName(n);

        System.out.println("IP address :" + ipadd);
    }

I have this program which finds the IP address. i want this to check whether it falls in Class A,Class B,Class C

Answer 1

class NetworkId{

static String findClass(String str){

int index = str.indexOf('.');

String ipsub = str.substring(0,index);

int ip = Integer.parseInt(ipsub);

// Class A

if (ip>=1 && ip<=126)

return "A";

// Class B

else if (ip>=128 && ip<=191)

return "B";

// Class C

else if (ip>=192 && ip<223)

return "C";

// Class D

else if (ip >=224 && ip<=239)

return "D";

// Class E

else

return "E";

}

static void separate(String str, String ipClass){

String network = "", host = "";

if(ipClass == "A"){

int index = str.indexOf('.');

network = str.substring(0,index);

host = str.substring(index+1,str.length());

}else if(ipClass == "B"){

int index = -1;

int dot = 2;

for(int i=0;i<str.length();i++){

if(str.charAt(i)=='.'){

dot -=1;

if(dot==0){

index = i;

break;

}

}

}

network = str.substring(0,index);

host = str.substring(index+1,str.length());

}else if(ipClass == "C"){

int index = -1;

int dot = 3;

for(int i=0;i<str.length();i++){

if(str.charAt(i)=='.'){

dot -=1;

if(dot==0){

index = i;

break;

}

}

}

network = str.substring(0,index);

host = str.substring(index+1,str.length());

}else if(ipClass == "D" || ipClass == "E"){

System.out.println("In this Class, IP address"+

" is not divided into Network and Host IDs");

return;

}

System.out.println("Network ID is "+network);

System.out.println("Host ID is "+host);

}

public static void main(String[] args) {

String str = "192.226.12.11";

String ipClass = findClass(str);

System.out.println("Given IP address belings to Class "+ipClass);

separate(str,ipClass);

}

}