CareerCup

import java.util.Arrays;
import java.util.List;

public class IPConvertToHex {


    public static void main(String[] args) {
        
        String ipHex = "";
        System.out.println(args[0]);
        
        List<String> ipAddress = Arrays.asList(args[0].split("\\.", 4));
        
        try{                      
            for (String s: ipAddress){
                s = String.format("%x", Integer.valueOf(s), 16);
                ipHex = ipHex + s;
            }
            System.out.println("0x"+ipHex);
        
        } catch (
                NullPointerException | 
                NumberFormatException | 
                UnsupportedOperationException e){
            
            System.out.println(e.getMessage() + "IP Address given is not supported.");
        }
    }
}

package SimpleTools;

import java.util.Arrays;
import java.util.List;

public class IPConvertToHex {

    public static final String NOT_SUPPORTED = "IP format not supported.";
    
    public static void main(String[] args) {       
        System.out.println("You input: " + args[0]); 
        System.out.println(IPConvertToHex(args[0]));      
    }
    
    public static String IPConvertToHex(String s){          
        
        //VALIDATE INPUT
        List<String> octets = Arrays.asList(s.split("\\."));         
        if (octets.size() != 4){  
            return NOT_SUPPORTED;  
        }
        for (String o : octets) {
            try {
                if (!(0 <=  Integer.parseInt(o) && 256 > Integer.parseInt(o))){
                    return NOT_SUPPORTED;
                }               
            } catch (NumberFormatException | NullPointerException e){
                return NOT_SUPPORTED;
            }
        }       
        
        //BUILD HEX STRING
        StringBuilder hexIP = new StringBuilder();
        hexIP.append("0x");                        
        octets.forEach(octet -> {
            hexIP.append(String.format("%x", Integer.valueOf(octet), 16));               
        });
        
        //OUTPUT
        return hexIP.toString();
   
   }
}

import java.util.ArrayList;
import java.util.Arrays;
import java.util.List;

public class HexConversion {

public static void main(String args[]){

String hex = "";
String input = args[0];

List<String> inputAsList = new ArrayList<String>();
inputAsList = Arrays.asList(input.split("\\.", 4));

try{
for(String s:inputAsList){

int i = Integer.parseInt(s);
s = ""+Integer.toHexString(i);
hex = hex+s;

}
System.out.println(hex);
}

catch(NullPointerException|NumberFormatException e){

System.out.println(e.getMessage()+"IP address not supported");

}

}

}