Using wrapper class in android studio

I've implemented a wrapper class according to this guide for the barcode functionality and when I try to use this wrapper class in my activity I get a nullpointerexception for the barcodeManager. When debugging I verify that the OnOpened method of the EMDKListener interface is not being called. Any hint? Here is the partial code for the wrapper class:


public class ZebraBarcode implements EMDKListener, DataListener, StatusListener{


    private Context mContext=null;

    private EMDKManager mEmdkManager=null;

    private BarcodeManager mBarcodeManager=null;

    private Scanner mScanner=null;

    private ScanDataCollection mScanDataCollection=null;

    private StatusData mStatusData=null;


    public ZebraBarcode(Context context){




    public boolean getEMDKManager(){

        boolean bManager=true;

        EMDKResults results = EMDKManager.getEMDKManager(mContext, this);

        if(results.statusCode != EMDKResults.STATUS_CODE.SUCCESS){



        return bManager;




    public void onOpened(EMDKManager emdkManager) {




In my activity I call this class:


if(Build.MANUFACTURER.contains("Zebra Technologies")

  || Build.MANUFACTURER.contains("Motorola Solutions")){

   mBarcodeSystem = new ZebraBarcode(mContext);