@Override protected void onSaveInstanceState(@NonNull Bundle outState) { super.onSaveInstanceState(outState); final View advancedPad = findViewById(R.id.pad_advanced); final View hexPad = findViewById(R.id.pad_hex); final View matrixPad = findViewById(R.id.pad_matrix); Panel panel = null; if (advancedPad.getVisibility() == View.VISIBLE) { panel = Panel.Advanced; } else if (hexPad.getVisibility() == View.VISIBLE) { panel = Panel.Hex; } else if (matrixPad.getVisibility() == View.VISIBLE) { panel = Panel.Matrix; } outState.putSerializable(KEY_PANEL, panel); }