What URI thinks are valid hosts

DomainValidator

import java.net.InetAddress;
import java.net.URI;

public class DomainValidator {

	public static String[] hosts = new String[] {
			"www.example.com",
			"example",
			"example9",
			"example-dash",
			"example_underscore",
			"_example_underscore",
			"-example-dash",
			"bücher",
	};

	public static void main(String[] args) {
		System.out.println("URI ================================");
		for (String host : hosts) {
			printURI(host);
		}
		System.out.println("\n");
		System.out.println("InetAddress ========================");
		for (String host : hosts) {
			printInetAddr(host);
		}
	}

	private static void printURI(String domain) {
		URI uri = URI.create("http://" + domain);
		if (uri.getHost() == null) {
			System.out.println("Error: "+domain + " is not a valid hostname.");
		} else {
			System.out.println(uri.getHost());
		}
	}

	private static void printInetAddr(String domain) {
		try {
			InetAddress addr = InetAddress.getByName(domain);
			System.out.println(addr.getCanonicalHostName());
		} catch (Exception e) {
			System.out.println("Error: "+ e.getMessage());
		}
	}
}

Results:

URI ================================
www.example.com
example
example9
example-dash
Error: example_underscore is not a valid hostname.
Error: _example_underscore is not a valid hostname.
Error: -example-dash is not a valid hostname.
Error: bücher is not a valid hostname.


InetAddress ========================
93.184.216.34
Error: example: unknown error
Error: example9: unknown error
Error: example-dash: unknown error
Error: example_underscore: unknown error
Error: _example_underscore: unknown error
Error: -example-dash: unknown error
Error: bücher: unknown error