同时从套接字读取和写入

Question

I'm writing an android app in java and I want to create a listener that receive messages in a while(true) loop, and also to be able to send messages to the server. For this task I'm using sockets with asyncTask . I have written a connectionHandler class which handle all the send and receive requests for my app.

So far so good, everything is working fluently for just sending and receiving messages one at a time, but I just couldn't find a way to do it simultaneously.

I need to execute the following code in a thread, but I don't know how to do it, because I have to return a String :

public static String receive() {
    try {
        return mConnectionHandler.new AsyncReceiveFromServer().execute()
                .get();
    } catch (InterruptedException e) {
        e.printStackTrace();
    } catch (ExecutionException e) {
        e.printStackTrace();
    }
    return null;
}

private class AsyncReceiveFromServer extends AsyncTask<Void, Void, String> {

    @Override
    protected String doInBackground(Void... params) {
        String result = null;
        try {
            result = in.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return result;
    }
}

When I'm running the receive function in a while(true) loop, I can't send messages, because the ...execute().get() is blocking the java class connectionHandler .

So to sum up, how can I execute the above code in a thread or any other asynchronous way? Or maybe you have any other suggestion to run the send and receive simultaneously while the receive is a while(true) loop?

Answer 1

First off- never use execute.get(). If you think you need to use it, you're architected wrong- it breaks the entire point of using a thread to have the calling thread wait for a result. If you just call execute, you'll run on another thread and work fine. If you need more than 1 thread running truly simultaneously, use executeOnExecutor() to override the 4.0 shared thread pool mechanism of AsyncTask.

Or better yet- don't use AsyncTask for this. You have something you want to run forever, waiting for input from a remote connection. This is a better fit for a Thread than an AsyncTask. I'd go with a thread and have the while loop built into the thread, and have the thread terminate only when the connection is closed.