Example Depot

// Create a selector and register two socket channels
Selector selector = null;
try {
    // Create the selector
    selector = Selector.open();

    // Create two non-blocking sockets. This method is implemented in
    // Creating a Non-Blocking Socket.
    SocketChannel sChannel1 = createSocketChannel("hostname.com", 80);
    SocketChannel sChannel2 = createSocketChannel("hostname.com", 80);

    // Register the channel with selector, listening for all events
    sChannel1.register(selector, sChannel1.validOps());
    sChannel2.register(selector, sChannel1.validOps());
} catch (IOException e) {
}

// Wait for events
while (true) {
    try {
        // Wait for an event
        selector.select();
    } catch (IOException e) {
        // Handle error with selector
        break;
    }

    // Get list of selection keys with pending events
    Iterator it = selector.selectedKeys().iterator();

    // Process each key at a time
    while (it.hasNext()) {
        // Get the selection key
        SelectionKey selKey = (SelectionKey)it.next();

        // Remove it from the list to indicate that it is being processed
        it.remove();

        try {
            processSelectionKey(selKey);
        } catch (IOException e) {
            // Handle error with channel and unregister
            selKey.cancel();
        }
    }
}

public void processSelectionKey(SelectionKey selKey) throws IOException {
    // Since the ready operations are cumulative,
    // need to check readiness for each operation
    if (selKey.isValid() && selKey.isConnectable()) {
        // Get channel with connection request
        SocketChannel sChannel = (SocketChannel)selKey.channel();

        boolean success = sChannel.finishConnect();
        if (!success) {
            // An error occurred; handle it

            // Unregister the channel with this selector
            selKey.cancel();
        }
    }
    if (selKey.isValid() && selKey.isReadable()) {
        // Get channel with bytes to read
        SocketChannel sChannel = (SocketChannel)selKey.channel();

        // See Reading from a SocketChannel
    }
    if (selKey.isValid() && selKey.isWritable()) {
        // Get channel that's ready for more bytes
        SocketChannel sChannel = (SocketChannel)selKey.channel();

        // See Writing to a SocketChannel
    }
}