class TransferThread extends Thread {
    private static final String TAG = "MainActivity";
    private static int TIMEOUT = 5000;
    private static int BUFFER_LENGTH = 32768;
    private byte[] buffer = new byte[BUFFER_LENGTH];

    UsbDeviceConnection connection;
    UsbEndpoint endpoint;

    TransferThread(UsbDeviceConnection connection, UsbEndpoint endpoint) {
        this.connection = connection;
        this.endpoint = endpoint;
    }

    public void run() {
        Log.v(TAG, "New thread started");

        UsbRequest usbRequest = new UsbRequest();
        if(usbRequest.initialize(connection, endpoint)) {
            Log.v(TAG, "USB request successfully initialised");
        }
        final ByteBuffer byteBuffer = ByteBuffer.allocate(BUFFER_LENGTH);
        if(usbRequest.queue(byteBuffer)) {
            Log.v(TAG, "USB request successfully queued");
        }
        if(connection.requestWait() == usbRequest) {
            Log.v(TAG, "Successfully returned USB request result");
            Log.v(TAG, "Has array: " + byteBuffer.hasArray());
            Log.v(TAG, "Data: " + Arrays.toString(byteBuffer.array()));
            Log.v(TAG, "Data: " + byteBuffer.toString());
        }
        else {
            Log.v(TAG, "Failed to return USB request");
        }

        Log.v(TAG, "byteBuffer.ToString(): " + byteBuffer.toString());

/*        int numBytesTransferred = connection.bulkTransfer(endpoint, buffer, buffer.length, TIMEOUT);
        if(numBytesTransferred >= 0) {
            Log.v(TAG, "Bulk transfer successful");
        }
        else {
            Log.v(TAG, "Bulk transfer failed");
        }*/
    }
}

public class MainActivity extends AppCompatActivity {

    private static final String TAG = "MainActivity";
    private static final String ACTION_USB_PERMISSION = "com.android.example.USB_PERMISSION";

    private final BroadcastReceiver usbReceiver = new BroadcastReceiver() {
        public void onReceive(Context context, Intent intent) {
            String action = intent.getAction();
            if (ACTION_USB_PERMISSION.equals(action)) {
                synchronized (this) {
                    UsbDevice device = (UsbDevice)intent.getParcelableExtra(UsbManager.EXTRA_DEVICE);
                    if (intent.getBooleanExtra(UsbManager.EXTRA_PERMISSION_GRANTED, false)) {
                        if(device != null){
                            Log.v(TAG,"Permission granted for device");
                        }
                    }
                    else {
                        Log.d(TAG, "permission denied for device " + device);
                    }
                }
            }
        }
    };

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        Log.v(TAG, "Running Main activity onCreate");

        // Enumerate USB devices
        UsbManager manager = (UsbManager) getSystemService(Context.USB_SERVICE);
        HashMap<String, UsbDevice> deviceList = manager.getDeviceList();
        Log.v(TAG, String.format("%d device(s) found by UsbManager", deviceList.size()));
        for (HashMap.Entry<String, UsbDevice> entry : deviceList.entrySet()) {
            String key = entry.getKey();
            Log.v(TAG, "Device name: " + key);
        }
        UsbDevice device = deviceList.get("/dev/bus/usb/002/002");
        Log.v(TAG, "Device info: " + device.toString());
        Log.v(TAG, String.format("Device has %d configuration(s)", device.getConfigurationCount()));
        Log.v(TAG, String.format("Device has %d interface(s)", device.getInterfaceCount()));

        // Obtain permission to communicate with a device
        PendingIntent permissionIntent = PendingIntent.getBroadcast(this, 0, new Intent(ACTION_USB_PERMISSION), PendingIntent.FLAG_MUTABLE);
        IntentFilter filter = new IntentFilter(ACTION_USB_PERMISSION);
        registerReceiver(usbReceiver, filter);
        manager.requestPermission(device, permissionIntent);

        int interfaceNumber = 0;
        int endpointNumber = 0;
        UsbInterface usbInterface = device.getInterface(interfaceNumber);
        Log.v(TAG, String.format("Got interface %d", interfaceNumber));
        Log.v(TAG, "Interface name: " + usbInterface.getName());
        Log.v(TAG, "Interface class: Vendor specific " + usbInterface.getInterfaceClass());
        UsbEndpoint endpoint = usbInterface.getEndpoint(endpointNumber);
        Log.v(TAG, String.format("Got endpoint %d", endpointNumber));
        int endpointType = endpoint.getType();
        if(endpointType == UsbConstants.USB_ENDPOINT_XFER_CONTROL) {
            Log.v(TAG, "Endpoint type: endpoint zero");
        }
        if(endpointType == UsbConstants.USB_ENDPOINT_XFER_ISOC) {
            Log.v(TAG, "Endpoint type: isochronous endpoint");
        }
        if(endpointType == UsbConstants.USB_ENDPOINT_XFER_BULK) {
            Log.v(TAG, "Endpoint type: bulk endpoint");
        }
        if(endpointType == UsbConstants.USB_ENDPOINT_XFER_INT) {
            Log.v(TAG, "Endpoint type: interrupt endpoint");
        }
        int endpointDir = endpoint.getDirection();
        if(endpointDir == UsbConstants.USB_DIR_IN) {
            Log.v(TAG, "Endpoint direction: IN (device to host)");
        }
        if(endpointDir == UsbConstants.USB_DIR_OUT) {
            Log.v(TAG, "Endpoint direction: OUT (host to device)");
        }

        UsbDeviceConnection connection = manager.openDevice(device);
        connection.claimInterface(usbInterface, true);

        TransferThread thread = new TransferThread(connection, endpoint);
        thread.start();
    }
}