Po modyfikacji kodu błąd nie wyskakuje, ale za to pojawia się inny java.lang.NullPointerException  Dołączam kod:    public void onClick(View vv) {
        new Thread(new Runnable(){
            @Override
            public void run() {
                try {
                    TextView kod_waluty[];
                    TextView kurs_sredni[];
                    try {
                        URL url = new URL("http://www.nbp.pl/kursy/xml/LastA.xml");
                        DocumentBuilderFactory dbf = DocumentBuilderFactory.newInstance();
                        DocumentBuilder db = dbf.newDocumentBuilder();
                        Document doc = db.parse(new InputSource(url.openStream()));
                        doc.getDocumentElement().normalize();
                        NodeList nodeList = doc.getElementsByTagName("pozycja");
                        kod_waluty = new TextView[nodeList.getLength()];
                        kurs_sredni = new TextView[nodeList.getLength()];
                        for (int i = 0; i < nodeList.getLength(); i++) {
                            Node node = nodeList.item(i);
                            Element kodElmnt = (Element) node;
                            NodeList kodList = kodElmnt.getElementsByTagName("kod_waluty");
                            Element kodElement = (Element) kodList.item(0);
                            kodList = kodElement.getChildNodes();
                            kod_waluty[i].setText(((Node) kodList.item(0)).getNodeValue());
                            Element kursElmnt = (Element) node;
                            NodeList kursList = kursElmnt.getElementsByTagName("kurs_sredni");
                            Element kursElement = (Element) kursList.item(0);
                            kodList = kursElement.getChildNodes();
                            kurs_sredni[i].setText(((Node) kursList.item(0)).getNodeValue());
                        }
                    } catch (Exception e) {
                        onClick.setText("Blad: " + e);
                    }
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
            }
        }).start();
    }