Get the IP address of the Host Computer

Programming Questions

un_bsd

Get the IP address of the Host Computer

in Programming Questions • 2 years ago

I've read the solution to 'Get the Host Name of the Computer' but it refers to an outside site you have to register to. I came up with the following code by converting the java code at http://www.exampledepot.com/egs/java.net/Local.html but I'm still looking for a way to get the Host Name and Host IP as separate values in a single line or declaration without having to make the list and strings as here:

/**
* HostName: Get Host Name and Ip Address
* PROCESSING EXAMPLE (UNBSD 2011) (BSD)
* Click Display to show ip and name in console.
*/
import java.net.InetAddress;
import java.net.UnknownHostException;
public String HostAddress;
public String HostName;
void setup(){
size(50,50);
}
void draw(){
// println(HostAddress + ":"+HostName);
}
void mouseClicked(){
try {
InetAddress addr = InetAddress.getLocalHost();
// Get IP Address
byte[] ipAddr = addr.getAddress();
// Extract Just the IP. Vanilla addr returns name and address separated by a '/' character
String raw_addr = addr.toString();
String[] list = split(raw_addr,'/');
HostAddress = list[1];
// Get hostname
HostName = addr.getHostName();
} catch (UnknownHostException e) {
}
println(HostAddress + ":"+HostName);
}

Any ideas on making this cleaner, faster? I'm going to see if I can put all the operative code in the setup part to make it run just once but I'm hoping there might be a more elegant or alternate function to use.

I haven't used the try method before. Does that work in Setup() or can it be called as a function from setup()? Can you explain try?

Replies(3)

cedrickie..

Re: Get the IP address of the Host Computer

2 years ago

i used this code in one of my older sketches

import java.net.InetAddress;

InetAddress inet;

String myIP;
try {
    inet = InetAddress.getLocalHost();
    myIP = inet.getHostAddress();
}
catch (Exception e) {
    e.printStackTrace();
    myIP = "couldnt get IP";
}
println(myIP);

PhiLho

Re: Get the IP address of the Host Computer

2 years ago

" Can you explain try?"
http://processing.org/reference/try.html

But, in short, Java uses exceptions to tell something... exceptional occurred. They can occur when trying to parse a string, for example (expecting a date or an integer, finding unrelated string) or when doing I/O (no space on disk, file not found, etc.) or, here, when computer has no network card, no Internet connection, etc.
These exceptions are thrown where they happen, and if not caught, can make the program to "crash" (to stop in error).
To avoid this, you put the risky code in a try block, and then you declare the catch clause(s), where you process the error.

Some errors are not critical, or are unexpected (NPE = Null Pointer Exception), so you can catch them but it is not mandatory. Other problems are more likely to happen (as said, I/O, parsing, HTTP...) so Java makes mandatory to catch them ("checked exceptions"). If you don't do that, you get an UncaughtException compilation error.

un_bsd

Re: Get the IP address of the Host Computer

2 years ago

Thanks folks. Cedrick, I found something similar to your code example except there's a library now for handling UnknownHostExceptions:

import java.net.InetAddress;
import java.net.UnknownHostException;

String HostName;
String Host Address;

<snip>

try {
    InetAddress addr = InetAddress.getLocalHost();

    // Get IP Address
    byte[] ipAddr = addr.getAddress();

    // Extract Just the IP. Vanilla addr returns name and address separated by a '/' character
    String raw_addr = addr.toString();
    String[] list = split(raw_addr,'/');
    HostAddress = list[1];

    // Get hostname
    HostName = addr.getHostName();
    }     catch (UnknownHostException e) {
}

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