DatagramSocket正在接收时，Android onTouchEvent无法正常工作

Question

I'm trying to allow my user to move a block around a screen while also listening for connected on a DatagramSocket, here is my onTouchEvent

public boolean onTouchEvent( MotionEvent event )
{
    if ( event.getAction() == MotionEvent.ACTION_DOWN )
    {
        if( event.getY() > getHeight() - 50 )
        {
            gameState.setRunning( false );
            ((Activity)getContext()).finish();
        }
        else
        {
            touched = true;
            Log.d(TAG, "Coords: x=" + event.getX() + ",y=" + event.getY());
        }
        checkCollisions( event.getX(), event.getY() );
    }

    if ( event.getAction() == MotionEvent.ACTION_MOVE )
    {
        checkCollisions( event.getX(), event.getY() );
    }

    if ( event.getAction() == MotionEvent.ACTION_UP ) 
    {
        touched = false;
    }
    return true;

}

And here is my server code

public void run()
{
    Log.d(TAG, "Ip address used:" + getLocalIPAddress() );
    while( true )
    {
        //Receive some data
        byte[] buf = new byte[256];
        DatagramPacket packet = new DatagramPacket( buf, buf.length );
        try 
        {
            socket.receive( packet );
        } 
        catch (IOException e) 
        {
            Log.d(TAG, "Error with receiving data");
            e.printStackTrace();
        }

        String data = new String( buf, 0, packet.getLength() );

        Log.d(TAG, "Data received was :" + data);

    }
}

Now my server works fine, but while the server is waiting for a connection, the client can't do anything, now I know a thread could be started, but won't that still block the onTouchEvent?

Canvas

Update

I implemented the run as a doInBackground using AsyncTask, it now works fine now without a problem, i can play with my application and also wait for clients to connect, this should work fine, Cheers for the help people.

Canvas

Answer 1

In Android, every View related aspects should be handled in the main thread, that is, the UI thread. Time consuming, heavy calculations or simple blocking tasks should remain in an another thread to avoid the user interface to be frozen.

Taking care of keeping your user interface fluid and responsive is important. If you don't, the ActivityManager will certainly end up popping up an alert box asking the user if he would like to close you application as it is not responding properly to his interactions. This called an ANR (Application not responding).

You might want to read this very good article talking about the responsiveness of every application should guarantee. It is written by the Google Android team and contains a lot of precious advises.

Answer 2

I need a bit more space than a comment ...

Key point: creating classes doesn't create threads, unless they are thread extending classes ( AsyncTask , Thread , etc).

Typically for your application the server would run in one thread, the game logic in another, the image updater in a third and the UI thread would refresh the display from this third thread when told that there was a new thing to display.

An example of a similar approach is given in http://www.javacodegeeks.com/2011/07/android-game-development-basic-game_05.html . I would suggest using that as a starting point and adding in an extra Server thread on a similar basis, which should get things going.

Sorry if I'm telling you stuff you already know, but better safe than sorry.