static void test() throws Exception {

        ServerSocketChannel ssc = null;

        SocketChannel sc = null;

        SocketChannel peer = null;

        try {

            ssc = ServerSocketChannel.open().bind(new InetSocketAddress(0));

            // loopback connection

            InetAddress lh = InetAddress.getLocalHost();

            sc = SocketChannel.open(new InetSocketAddress(lh, ssc.socket().getLocalPort()));

            peer = ssc.accept();

            // peer sends message so that "sc" will be readable

            int n = peer.write(ByteBuffer.wrap("Hello".getBytes()));

            assert n > 0;

            sc.configureBlocking(false);

            Selector selector = Selector.open();

            SelectionKey key = sc.register(selector, SelectionKey.OP_READ |

                SelectionKey.OP_WRITE);

            boolean done = false;

            int failCount = 0;

            while (!done) {

                if (selector.select() > 0) {

                    Set<SelectionKey> keys = selector.selectedKeys();

                    Iterator<SelectionKey> iterator = keys.iterator();

                    while (iterator.hasNext()) {

                        key = iterator.next();

                        iterator.remove();

                        if (key.isWritable()) {

                            failCount++;

                            if (failCount > 10)

                                throw new RuntimeException("Test failed");

                            Thread.sleep(250);

                        }

                        if (key.isReadable()) {

                            done = true;

                        }

        } finally {

            if (peer != null) peer.close();

            if (sc != null) sc.close();

            if (ssc != null) ssc.close();