Hiding a UI element when target is not detected.

Hi Everyone,

I am working on Android with Java API. I want to show a button when the marker is detected and hide it when the marker is not detected just like the teapot. I can successfully show the button when any target (chips and stones) are detected. Thanks to the tutorial provided by Vuforia (“triggering-ui-events-when-target-detected”). 

However, now that I can show the hidden button once the target is detected, it doesn’t hide when the target is no longer available. I am assuming that I might need to get the TrackerManager instance just like doLoadTrackersData() and doUnloadTrackersData() methods and find if the mCurrentDataset is active or not. However so far, I have failed miserably understanding this issue. Kindly help….  My onResume() code is below:

@Override
	protected void onResume() {
		Log.d(LOGTAG, "onResume");
		super.onResume();
		displayMessageHandler = new Handler() {
			@Override
			public void handleMessage(Message msg) {

				TrackerManager tManager = TrackerManager.getInstance();
				ImageTracker imageTracker = (ImageTracker) tManager
						.getTracker(ImageTracker.getClassType());

				String text = (String) msg.obj;

				Toast.makeText(getApplicationContext(), text,
						Toast.LENGTH_SHORT).show();

				
					if (text.equalsIgnoreCase("stones")) {
						Log.e("Is it Stones", text);
						b3.setBackgroundResource(R.drawable.up);
						b3.startAnimation(shake);
						b3.setVisibility(View.VISIBLE);
					} else if (text.equalsIgnoreCase("chips")) {
						Log.e("Is it chips", text);
						b3.setBackgroundResource(R.drawable.up);
						b3.startAnimation(shake);
						b3.setVisibility(View.VISIBLE);

					} else {
						Log.e("ELSE", text);
						b3.setVisibility(View.GONE);
					}
				}
			
		};

		// This is needed for some Droid devices to force portrait
		if (mIsDroidDevice) {
			setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_LANDSCAPE);
			setRequestedOrientation(ActivityInfo.SCREEN_ORIENTATION_PORTRAIT);
		}

		try {
			vuforiaAppSession.resumeAR();
		} catch (SampleApplicationException e) {
			Log.e(LOGTAG, e.getString());
		}

		// Resume the GL view:
		if (mGlView != null) {
			mGlView.setVisibility(View.VISIBLE);
			mGlView.onResume();
		}

	}