Creating InetAddress object in Java

I am trying to convert an address specified by an IP number or a name, both in String (i.e. localhost or 127.0.0.1), into an InetAdress object. There's no constructor but rather static methods that return an InetAddress. So if I get a host name it's not a problem, but what if I get the IP number? There's one method that gets byte[] but I'm no开发者_如何学JAVAt sure how that can help me. All other methods gets the host name.

InetAddress API documentation

You should be able to use getByName or getByAddress.

The host name can either be a machine name, such as "java.sun.com", or a textual representation of its IP address

InetAddress addr = InetAddress.getByName("127.0.0.1");

The method that takes a byte array can be used like this:

byte[] ipAddr = new byte[]{127, 0, 0, 1};
InetAddress addr = InetAddress.getByAddress(ipAddr);

From the API for InetAddress

The host name can either be a machine name, such as "java.sun.com", or a textual representation of its IP address. If a literal IP address is supplied, only the validity of the address format is checked.

ip = InetAddress.getByAddress(new byte[] {
        (byte)192, (byte)168, (byte)0, (byte)102}
);

InetAddress.getByName also works for ip address.

From the JavaDoc

The host name can either be a machine name, such as "java.sun.com", or a textual representation of its IP address. If a literal IP address is supplied, only the validity of the address format is checked.

The api is fairly easy to use.

// Lookup the dns, if the ip exists.
 if (!ip.isEmpty()) {
     InetAddress inetAddress = InetAddress.getByName(ip);
     dns = inetAddress.getCanonicalHostName(); 
 }

InetAddress class can be used to store IP addresses in IPv4 as well as IPv6 formats. You can store the IP address to the object using either InetAddress.getByName() or InetAddress.getByAddress() methods.

In the following code snippet, I am using InetAddress.getByName() method to store IPv4 and IPv6 addresses.

InetAddress IPv4 = InetAddress.getByName("127.0.0.1");
InetAddress IPv6 = InetAddress.getByName("2001:db8:3333:4444:5555:6666:1.2.3.4");

You can also use InetAddress.getByAddress() to create object by providing the byte array.

InetAddress addr = InetAddress.getByAddress(new byte[]{127, 0, 0, 1});

Furthermore, you can use InetAddress.getLoopbackAddress() to get the local address and InetAddress.getLocalHost() to get the address registered with the machine name.

InetAddress loopback = InetAddress.getLoopbackAddress(); // output: localhost/127.0.0.1
InetAddress local = InetAddress.getLocalHost(); // output: <machine-name>/<ip address on network>

Note- make sure to surround your code by try/catch because InetAddress methods return java.net.UnknownHostException

This is a project for getting IP address of any website , it's usefull and so easy to make.

import java.net.InetAddress;
import java.net.UnkownHostExceptiin;

public class Main{
    public static void main(String[]args){
        try{
            InetAddress addr = InetAddresd.getByName("www.yahoo.com");
            System.out.println(addr.getHostAddress());

          }catch(UnknownHostException e){
             e.printStrackTrace();
        }
    }
}