single-threaded server based on Java NIO selector

NioSelectorServer.java

package acme;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.SelectionKey;
import java.nio.channels.Selector;
import java.nio.channels.ServerSocketChannel;
import java.nio.channels.SocketChannel;
import java.util.Iterator;

public class NioSelectorServer {

    public static void main(String[] args) throws IOException {

        ServerSocketChannel server = ServerSocketChannel.open();
        server.bind(new InetSocketAddress("localhost", 5454));
        server.configureBlocking(false);

        Selector selector = Selector.open();
        server.register(selector, SelectionKey.OP_ACCEPT);
        ByteBuffer buffer = ByteBuffer.allocate(256);

        while (true) {

            selector.select();
            Iterator<SelectionKey> keys = selector.selectedKeys().iterator();
            while (keys.hasNext()) {

                SelectionKey key = keys.next();

                if (key.isAcceptable()) {
                    SocketChannel client = server.accept();
                    register(selector, client);
                }
                if (key.isReadable()) {
                    SocketChannel client = (SocketChannel) key.channel();
                    processRequest(buffer, client);
                }
                keys.remove();
            }
        }
    }

    private static void processRequest(ByteBuffer buffer, SocketChannel client) throws IOException {
        client.read(buffer);
        if (new String(buffer.array()).trim().equals("EXIT")) {
            client.close();
        }
        buffer.flip();
        client.write(buffer);
        buffer.clear();
    }

    private static void register(Selector selector, SocketChannel client) throws IOException {
        client.configureBlocking(false);
        client.register(selector, SelectionKey.OP_READ);
    }
}