I am using a webrtc sample Code to stream from my Android device to a Webpage. The sample Code does not have the function to Switch the camera. I tried to solve it but I failed. The sample uses a VideoCapturerAndroid class all of the Suggestions I found switching the camera used a different type.
The main part of the sample Looks like this:
@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_video_chat);
    ButterKnife.bind(this);
    getWindow().addFlags(WindowManager.LayoutParams.FLAG_KEEP_SCREEN_ON);
    Bundle extras = getIntent().getExtras();
    if (extras == null || !extras.containsKey(Constants.USER_NAME)) {
        Intent intent = new Intent(this, MainActivity.class);
        startActivity(intent);
        Toast.makeText(this, "Need to pass username to VideoChatActivity in intent extras (Constants.USER_NAME).", Toast.LENGTH_SHORT).show();
        finish();
        return;
    }
    this.username = extras.getString(Constants.USER_NAME, "");
    this.mCallStatus = (TextView) findViewById(R.id.call_status);
    // First, we initiate the PeerConnectionFactory with our application context and some options.
    PeerConnectionFactory.initializeAndroidGlobals(
            this,  // Context
            true,  // Audio Enabled
            true,  // Video Enabled
            true,  // Hardware Acceleration Enabled
            null); // Render EGL Context
    pcFactory = new PeerConnectionFactory();
    this.pnRTCClient = new PnRTCClient(Constants.PUB_KEY, Constants.SUB_KEY, this.username);
    List<PeerConnection.IceServer> servers = getXirSysIceServers();
    if (!servers.isEmpty()) {
        this.pnRTCClient.setSignalParams(new de.kevingleason.pnwebrtc.PnSignalingParams());
    }
    backFacingCam = VideoCapturerAndroid.getNameOfBackFacingDevice();
    frontFacingCam = VideoCapturerAndroid.getNameOfFrontFacingDevice();
    // Creates a VideoCapturerAndroid instance for the device name
    //VideoCapturer capturer = VideoCapturerAndroid.create(frontFacingCam);
    capturer = VideoCapturerAndroid.create(facingCam);
    // First create a Video Source, then we can make a Video Track
    localVideoSource = pcFactory.createVideoSource(capturer, this.pnRTCClient.videoConstraints());
    localVideoTrack = pcFactory.createVideoTrack(VIDEO_TRACK_ID, localVideoSource);
    // First we create an AudioSource then we can create our AudioTrack
    AudioSource audioSource = pcFactory.createAudioSource(this.pnRTCClient.audioConstraints());
    AudioTrack localAudioTrack = pcFactory.createAudioTrack(AUDIO_TRACK_ID, audioSource);
    // To create our VideoRenderer, we can use the included VideoRendererGui for simplicity
    // First we need to set the GLSurfaceView that it should render to
    this.videoView = (GLSurfaceView) findViewById(R.id.gl_surface);
    // Then we set that view, and pass a Runnable to run once the surface is ready
    VideoRendererGui.setView(videoView, null);
    // Now that VideoRendererGui is ready, we can get our VideoRenderer.
    // IN THIS ORDER. Effects which is on top or bottom
    remoteRender = VideoRendererGui.create(0, 0, 100, 100, VideoRendererGui.ScalingType.SCALE_ASPECT_FILL, false);
    localRender = VideoRendererGui.create(0, 0, 100, 100, VideoRendererGui.ScalingType.SCALE_ASPECT_FILL, true);
    // We start out with an empty MediaStream object, created with help from our PeerConnectionFactory
    // Note that LOCAL_MEDIA_STREAM_ID can be any string
    MediaStream mediaStream = pcFactory.createLocalMediaStream(LOCAL_MEDIA_STREAM_ID);
    // Now we can add our tracks.
    mediaStream.addTrack(localVideoTrack);
    mediaStream.addTrack(localAudioTrack);
    // First attach the RTC Listener so that callback events will be triggered
    this.pnRTCClient.attachRTCListener(new DemoRTCListener());
    // Then attach your local media stream to the PnRTCClient.
    //  This will trigger the onLocalStream callback.
    this.pnRTCClient.attachLocalMediaStream(mediaStream);
    this.pnRTCClient.listenOn(username);
    this.pnRTCClient.setMaxConnections(1);
    ....
}
Currently I am hardcoding which camera shall be used:
    backFacingCam = VideoCapturerAndroid.getNameOfBackFacingDevice(); 
    frontFacingCam = VideoCapturerAndroid.getNameOfFrontFacingDevice();
This is my button which shall Switch the camera:
@OnClick(R.id.switchCameraBtn)
public void switchCameraBtn(View view) {
    Log.e("Test", "switch camera button clicked");
    this.mCallStatus = (TextView) findViewById(R.id.call_status);
}
I also tried to restart the activity and give a Parameter which tells one that the other camera shall be used, but I would like to Keep the stream fluent and not to restart the activity.