Question

I developed an Rss Application for Blackberry(java) and i successfully displayed Titles(List of Radio Channels need to play online)from Rss File.i already developed code for playing those List of Radio channels,but my requirement is to play First channel(First List)when my List initially(List of Channels) displayed,can any one help me where can i write my logic(Playing first channel by default) to get execute after my channels displayed immediately?

Here my code for Rss:

public class RssScreen extends MainScreen implements ListFieldCallback,FieldChangeListener {
    Connection _connectionthread;     
    private static ListField _list;
    String image;
    String title;
    private static Vector listElements = new Vector();
    private static Vector listImage = new Vector();

    public long mycolor ;
    VerticalFieldManager mainManager;
    VerticalFieldManager subManager;
    int selectedList;
    Radio radio;

    public RssScreen(){
        final Bitmap backgroundBitmap = Bitmap.getBitmapResource("blackbackground.png");

         mainManager = new VerticalFieldManager(Manager.NO_VERTICAL_SCROLL | Manager.NO_VERTICAL_SCROLLBAR )
            {

             public void paint(Graphics graphics)
              {
                graphics.drawBitmap(0, 0, Display.getWidth(),Display.getHeight(),backgroundBitmap, 0, 0);

                super.paint(graphics);
              }

            };

            subManager = new VerticalFieldManager(Manager.VERTICAL_SCROLL | Manager.VERTICAL_SCROLLBAR )
            {
                protected void sublayout( int maxWidth, int maxHeight )
                {
                    int displayWidth = Display.getWidth();
                    int displayHeight = Display.getHeight();

                    super.sublayout( displayWidth, displayHeight);
                    setExtent( displayWidth, displayHeight);
                }
            };        


        add(mainManager);


        _list = new ListField()

        {
            protected boolean navigationClick(int status, int time)
            {
                            return true;
            }
        public void paint(Graphics graphics)

        {
            graphics.setColor((int) mycolor);
        super.paint(graphics);

        }

        };
        mycolor = 0x00FFFFFF;
            _list.invalidate();
            _list.setEmptyString("* Feeds Not Available *", DrawStyle.HCENTER);
        _list.setRowHeight(50);

        _list.setCallback(this);
        mainManager.add(subManager);    
       listElements.removeAllElements();
       _connectionthread = new Connection(); 
       _connectionthread.start();
     }

    private class Connection extends Thread
    { 
        public Connection()
        { 
           super(); 
        } 

        public void run() {  
            Document doc;  
            StreamConnection conn = null; 
            InputStream is = null;  
            try {           

                conn = (StreamConnection) Connector.open("http://toucheradio.com/toneradio/android/toriLite/toriplaylist.xml"+";deviceside=true");          

                DocumentBuilderFactory docBuilderFactory = DocumentBuilderFactory.newInstance();  
                docBuilderFactory.setIgnoringElementContentWhitespace(true);
                docBuilderFactory.setCoalescing(true);
                DocumentBuilder docBuilder = docBuilderFactory.newDocumentBuilder();    
                docBuilder.isValidating();      
                is = conn.openInputStream();    
                doc = docBuilder.parse(is);     
                doc.getDocumentElement().normalize();   
                NodeList listImg = doc.getElementsByTagName("title"); 
                for (int i = 0; i < listImg.getLength(); i++) {    
                Node textNode = listImg.item(i).getFirstChild();  
                listElements.addElement(textNode.getNodeValue());
                 image=textNode.getNodeValue();             
                }
                NodeList list = doc.getElementsByTagName("image"); 
                    for (int a = 0; a < list.getLength(); a++) {    
                    Node textNode1 = list.item(a).getFirstChild();  
                    listImage.addElement(textNode1.getNodeValue());
                                        }





            }
                     catch (Exception e) {   
                        System.out.println(e.toString());                     
                        } finally {   
                            if (is != null) {  
                            try { is.close(); 
                            } catch (IOException ignored) {}   
                            }        if (conn != null) {  
                                try { conn.close(); } 
                                catch (IOException ignored) {} 
                                }    } UiApplication.getUiApplication().invokeLater(new Runnable() { 
                                    public void run() {         
                                    _list.setSize(listElements.size()); 

                                    subManager.add(_list);

                                    invalidate();
                                    }   
                                    });
                                }

    }


    public void drawListRow(ListField list, Graphics g, int index, int y, int w) 
    {  
     String title=(String)listElements.elementAt(index);
     String image=(String)listImage.elementAt(index);
    // Bitmap image1= getBitmapFromUrl(image);


     System.out.println("Title"+title);
     System.out.println("Image"+image);
        int yPos = 0+y;
        g.drawLine(0, yPos, w, yPos);

        g.drawText(title, 0, y, 0, w);
       // g.drawBitmap(0,y,image1.getWidth(),image1.getHeight(),image1,0,0);

    }


    public Object get(ListField list, int index) 
    {
        return listElements.elementAt(index); 
    } 
    public int indexOfList(ListField list, String prefix, int string) 
    { 
        return listElements.indexOf(prefix, string); 
    } 
    public int getPreferredWidth(ListField list) 
    { 
     return Display.getWidth(); 
    } 
    public void insert(String toInsert, int index) {
        listElements.addElement(toInsert);
        }

    public void fieldChanged(Field field, int context) {




    }

    }

Answer 1

Check following methods of the class Field:

• protected void onDisplay()
• protected void onExposed()

Also similar methods from Screen can be used. Check the followings:

• protected void onUiEngineAttached(boolean attached)
• protected void onExposed()
• protected void onDisplay()