java - 黑莓 java ListField

Question

我为Blackberry(java)开发了一个Rss应用程序，并且成功地从Rss文件中显示了标题(需要在线播放的广播 channel 列表)。我已经开发了用于播放这些广播 channel 列表的代码，但我的要求是播放第一个 channel (第一个列表)当我的列表最初显示( channel 列表)时，任何人都可以帮助我在哪里可以编写我的逻辑(默认情况下播放第一个 channel )以便在我的 channel 立即显示后执行？

这是我的 Rss 代码:

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

检查类的以下方法 Field :

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

还有来自 Screen 的类似方法可以使用。检查以下内容:

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