Java NIO -- DatagramChannel

package com.soyoungboy.nio;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.util.Date;
import java.util.Iterator;
import java.util.Scanner;

import org.junit.Test;

public class TestDatagramChannel {
    
    @Test
    public void send() throws IOException{
        DatagramChannel dc = DatagramChannel.open();
        
        dc.configureBlocking(false);
        
        ByteBuffer buf = ByteBuffer.allocate(1024);
        
        Scanner scan = new Scanner(System.in);
        
        while(scan.hasNext()){
            String str = scan.next();
            buf.put((new Date().toString() + ":\n" + str).getBytes());
            buf.flip();
            dc.send(buf, new InetSocketAddress("127.0.0.1", 9898));
            buf.clear();
        }
        
        dc.close();
    }
    
    @Test
    public void receive() throws IOException{
        DatagramChannel dc = DatagramChannel.open();
        
        dc.configureBlocking(false);
        
        dc.bind(new InetSocketAddress(9898));
        
        Selector selector = Selector.open();
        
        dc.register(selector, SelectionKey.OP_READ);
        
        while(selector.select() > 0){
            Iterator<SelectionKey> it = selector.selectedKeys().iterator();
            
            while(it.hasNext()){
                SelectionKey sk = it.next();
                
                if(sk.isReadable()){
                    ByteBuffer buf = ByteBuffer.allocate(1024);
                    
                    dc.receive(buf);
                    buf.flip();
                    System.out.println(new String(buf.array(), 0, buf.limit()));
                    buf.clear();
                }
            }
            
            it.remove();
        }
    }

}