Displaying a string in a TextView?

Question

Java

Once a second, data arrives via USB
on arrival starts

UsbSerialInterface.UsbReadCallback mCallback = new UsbSerialInterface.UsbReadCallback() {
        // Определение метода обратного вызова, который вызывается при приеме данных.
        @Override
        public void onReceivedData(byte[] arg0) {

           // data = null;
            try {
                data = new String(arg0, "UTF-8");
                // data.concat("/n");
                runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                            speed.setText(data);
                    }
                });

            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            }
        }
    };

but the value in speed will appear for a fraction of a second and disappear, how to make the text in speed not disappear?