How to join the room with Socket.IO (Android)

I use the Android version of native Socket.IO to create a program using Socket.IO.
Note: http://socket.io/blog/native-socket-io-and-android/

Environment:
Android Target Version: android-19
Eclipse Luna Service Release 2 (4.4.2)

I'm looking for a method to enter room, but I can't find it.

private Socket mSocket;
{
    try{
        mSocket=IO.socket("http://[Socket.io]/");
    } catch(URISyntaxExceptione){}
}

protected void onCreate (Bundle savedInstanceState) {
mSocket.connect();
mSocket.emit("from_client", "Android"");
    ・・・     
}

I succeeded in sending the message.Is there any way to enter the room in the Android version of Socket.IO?
Please let me know if you know.