Question

I am a newbie of Blackberry developing application. I try to store all xml parsing data to an object, and set them to a vector.

public class XmlParser extends MainScreen {
    Database d;
    private HttpConnection hcon = null;

    private Vector binN;
    public Vector getBinN() {
        return binN;
    }

    public void setBinN(Vector bin) {
        this.binN = bin;
    }

    LabelField from;
    LabelField ttl;
    LabelField desc;
    LabelField date;

    public XmlParser() {
        LabelField title = new LabelField("Headline News" ,LabelField.HCENTER|LabelField.USE_ALL_WIDTH);
        setTitle(title);

        try {
            URI myURI = URI.create("file:///SDCard/Database/WebFeed.db"); 
            d = DatabaseFactory.open(myURI);
            Statement st = d.createStatement("SELECT feed_url, feed_name FROM WebFeed");
            st.prepare();
            Cursor c = st.getCursor();
            while (c.next()) {
                Row r = c.getRow();
                hcon = (HttpConnection)Connector.open(r.getString(0));
                hcon.setRequestMethod(HttpConnection.GET);
                        hcon.setRequestProperty("User-Agent", "Profile/MIDP-1.0 Configuration/CLDC-1.0");
                        hcon.setRequestProperty("Content-Length", "0");
                        hcon.setRequestProperty("Connection", "close");
                DocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();
                DocumentBuilder builder = factory.newDocumentBuilder();

                builder.isValidating();
                Document document = builder.parse(hcon.openInputStream());

                Element rootElement = document.getDocumentElement();
                rootElement.normalize();

                NodeList list = document.getElementsByTagName("item");

                int i=0;
                while (i<10){
                    Node item = list.item(i);
                    if(item.getNodeType() != Node.TEXT_NODE) {
                        NodeList itemChilds = item.getChildNodes();
                        int j=0;
                        while (j<10){
                            Node detailNode = itemChilds.item(j);
                            if(detailNode.getNodeType() != Node.TEXT_NODE) {                                
                                if(detailNode.getNodeName().equalsIgnoreCase("title")) {
                                    ttl = new LabelField(getNodeValue(detailNode)) {
                                        public void paint(Graphics g) {
                                            g.setColor(Color.BLUE);
                                            super.paint(g);
                                        }
                                    };
                                    from = new LabelField(r.getString(1), LabelField.FIELD_RIGHT|LabelField.USE_ALL_WIDTH);
                                    ttl.setFont(Font.getDefault().derive(Font.BOLD));
                                    from.setFont(Font.getDefault().derive(Font.BOLD));
                                    add (from);
                                    add (ttl);
                                } else if(detailNode.getNodeName().equalsIgnoreCase("description")) {

                                    desc = new LabelField(getNodeValue(detailNode), 0, 70, USE_ALL_WIDTH);
                                    add(desc);
                                } else if(detailNode.getNodeName().equalsIgnoreCase("dc:date")) {
                                    date = new LabelField(getNodeValue(detailNode), 11, 5, USE_ALL_WIDTH) {
                                        public void paint(Graphics g) {
                                            g.setColor(Color.ORANGE);
                                            super.paint(g);
                                        }
                                    };
                                    add(date);
                                    add(new SeparatorField());
                                } else if(detailNode.getNodeName().equalsIgnoreCase("pubDate")) {
                                    date = new LabelField(getNodeValue(detailNode), 0, 22, USE_ALL_WIDTH) {
                                        public void paint(Graphics g) {
                                            g.setColor(Color.ORANGE);
                                            super.paint(g);
                                        }
                                    };
                                    add(date);
                                    add(new SeparatorField());
                                } else {
                                    System.out.println("not the node");
                                }
                            } else {
                                System.out.println("not text node");
                            }
                            j++;
                        }
                    }
                    i++;
                    BinNews bin = new BinNews();
                    bin.setProv(from.getText());
                    bin.setTitle(ttl.getText());
                    bin.setDesc(desc.getText());
                    bin.setDate(date.getText());
                    binN.addElement(bin);
                }
                setBinN(binN);
            }
            //setBinN(binN);
            st.close();
            d.close();
        } catch (Exception e)  {
            add (new LabelField(e.toString(),LabelField.HCENTER|LabelField.USE_ALL_WIDTH));
            System.out.println(e.toString());
        }
    }

    public String getNodeValue(Node node) {
        NodeList nodeList = node.getChildNodes();
        Node childNode = nodeList.item(0);
        return childNode.getNodeValue();
    }
}

I try to store all data from an object called BinNews, to a vector called binN. But when I do debugging, I found that BinN has null value, because “binN.addElement(bin)” doesn’t work.
Please advise.

Answer 1

First, you don’t actually call setBinN until after the while(i < 10) loop completes. So when you say binN.addElement(bin) then binN will be null.

However your setBinN(binN) call doesn’t make sense because you’re passing in binN and then setting it to itself which isn’t going to do anything.

What you can do is have binN = new Vector(); at the top of the constructor and then it won’t be null later on. I don’t think the setBinN call will be necessary later on if you’re adding the BinNews objects straight to binN.