Android USB Device Communication

try
{
    UsbDeviceConnection connection = manager.openDevice(device);
    UsbInterface intf = device.getInterface(0);
    UsbEndpoint endpoint = intf.getEndpoint(0);
    int direction = endpoint.getDirection();
    Toast.makeText(StartActivity.this,"Direction Of Data Transfer :"+direction,Toast.LENGTH_SHORT).show();
    ByteBuffer recvBuffer = ByteBuffer.allocate(endpoint.getMaxPacketSize());
    recvBuffer.clear();
    UsbRequest request = new UsbRequest();
    request.initialize(connection, endpoint);
    UsbRequest finishReq;
    while ((finishReq = connection.requestWait()) != request) {
        if (finishReq == null)
            throw new IOException("Request failed.");
        int res  = connection.bulkTransfer(endpoint,b,"Hello".length(), 100);
        if(res==1)
            Toast.makeText(this, "Failed :" , Toast.LENGTH_LONG).show();
        
        Thread.sleep(100);
    }
}
catch(Exception e)
{
    Toast.makeTest(this,"Exception :"+e.getMessagage,Toast.LENGTH_LONG).show();
}