WebRTC onMessage() does not trigger on Android

I have tried to implement datachannel on Android. I successfully send the data from android to web using datachannel.

However, whenever I try to send the data from the web to android, android doesn't receive the data and onMessage() is never triggered.

I don't understand why this happens. Here is how I implement DataChannel.Observer.

private class DcObserver implements DataChannel.Observer {
 // removed other overrided messages for clarity
 @Override
 public void onMessage(DataChannel.Buffer buffer) {
   Toast.makeText(getApplicationContext(),
                   "Some Data has been received", Toast.LENGTH_SHORT)
                   .show();
   Log.d("Data", "Some Data has been received");
 }
}

I create the object for every PeerConnection object. I have this class which contains the PeerConnection object.

private class FilePeer implements SdpObserver {
 private PeerConnection pc;
 private DataChannel dc;
 // removed other overrided methods for clarity
 public FilePeer() {
   PcObserver pcObserver = new PcObserver();

   pc = factory.createPeerConnection(RTCConfig.getIceServer(), 
       RTCConfig.getMediaConstraints(), pcObserver);

   dc = pc.createDataChannel("sendDataChannel", new DataChannel.Init());

    //DcObserver dcObserver = new DcObserver();

    //dc.registerObserver(dcObserver);    // This one crashes the app, therefore, getting the datachannel using onDataChannel
 }
}

This is how PcObserver class looks like.

private class PcObserver implements PeerConnection.Observer{

 @Override
 public void onDataChannel(final DataChannel dataChannel) {

  runOnUiThread(new Runnable() {
     public void run() {
         peer.dc = dataChannel;

         DcObserver dcObserver = new DcObserver();

         peer.dc.registerObserver(dcObserver);

         //dataChannel.registerObserver(dcObserver);
     }
   });
 }
 // other methods are removed for clarity
}

I think I am doing something wrong with peer.dc.registerObserver(dcObserver); But I don't know what.

I found the solution for this problem on webrtc group.

I need to hold on to a reference of the observer to make sure it does not get destroyed when the DataChannel calls back.

One more thing, we need to do is remove peer.dc = dataChannel; inside onDataChannel();,

The following code works fine for me now:

    public void onDataChannel(final DataChannel dataChannel) {
        final DataChannel dc = dataChannel;
        runOnUiThread(new Runnable() {
              public void run() {

                    DcObserver dcObserver = new DcObserver();

                    peer.dc.registerObserver(dcObserver);

              }
            });


    }