BlackBerry listfield development

Question

任何人都可以建议我如何在黑莓中创建一个可单击的列表字段，以便点击一个项目时必须出现一个新的画面。

Answer 1

我在JDE 5.0上用VerticalFieldManager和自定义扩展字段做了类似的工作。

我假设你有一个你想在主屏幕上显示的对象列表。

首先;创建一个为您的列表项目扩展Field的类，根据您的要求重写其绘制方法，布局方法和其他事件。

接下来，创建一个您想要显示列表的主屏幕。一旦你填充了你的对象列表，在一个循环中，将每个对象模型传递给先前创建的字段的构造函数。然后将fieldChanged事件添加到该字段并将其添加到verticalFieldManager。

您需要重写事件（如fieldChanged事件），因为您想单击它并在另一个屏幕上显示其细节。

最后，创建一个详细信息屏幕，其中显示您的列表项目的对象详细信息所需的参数。在主屏幕实现的fieldChanged事件中，将对象传递给详细信息屏幕并推送详细信息屏幕。

另外，this方法可能对您有用。

实施例：

自定义字段：

public class CListItemField extends Field { 

    private CListItemModel model; 

    public CListItemField(CListItemModel _model, long style) { 
     super(style); 
     this.model = _model; 
    } 

    public CListItemModel getModel() { 
     return this.model; 
    } 

    // overrides 

    public int getPreferredHeight() { 
     //return custom height 
    } 

    public int getPreferredWidth() { 
     //return custom width 
    } 

    protected void layout(int width, int height) { 
     setExtent(Math.min(width, getPreferredWidth()), getPreferredHeight()); 
    } 

    protected void paint(Graphics g) { 

     //custom paint stuff (borders, fontstyle, text position, icons etc.) 

     if (isFocus()) { 
      //focused item display settings 

     } else { 
      //item display settings 
     } 

    } 

    protected void drawFocus(Graphics graphics, boolean on) { 
    } 

    public boolean isFocusable() { 
     return true; 
    } 

    protected void onFocus(int direction) { 
     super.onFocus(direction); 
     invalidate(); 
    } 

    protected void onUnfocus() { 
     super.onUnfocus(); 
     invalidate(); 
    } 

    protected boolean navigationClick(int status, int time) { 
     fieldChangeNotify(0); 
     return true; 
    } 

    protected boolean keyChar(char character, int status, int time) { 
     //send key event to listener 
     if (character == Keypad.KEY_ENTER) { 
      fieldChangeNotify(0); 
      return true; 
     } 
     return super.keyChar(character, status, time); 
    } 

} 

列表屏幕：

public class ScreenListbox extends MainScreen implements FieldChangeListener, FocusChangeListener { 

private VerticalFieldManager verticalField; 
private Vector listItemVector; 

public ScreenOttoInbox(String title) { 
    super(title, Manager.NO_VERTICAL_SCROLL); 
    setData(); 
    setComponents(); 
} 

private void setData() { 
    //populate listItemVector according to your business (ie. read json response then parse it and collect it to a vector) 
} 

public void setComponents() { 
    verticalField = new VerticalFieldManager(Manager.VERTICAL_SCROLL | Manager.VERTICAL_SCROLLBAR); 
    setListContent(verticalField, listItemVector); 
    add(verticalField); 
} 

private void setListContent(VerticalFieldManager field, Vector vector) { 
    try { 
     int vlen = vector.size(); 
     for (int i = 0; i < vlen; i++) { 
      CListItemModel model = (CListItemModel) vector.elementAt(i); 
      CListItemField itemField = new CListItemField(model, Field.FOCUSABLE | Field.ACTION_INVOKE); 
      itemField.setChangeListener(this); 
      itemField.setFocusListener(this); 
      field.add(itemField); 
     } 
    } catch (Exception ex) { } 
} 

protected boolean onSavePrompt() { 
    return true; 
} 

public void fieldChanged(Field field, int context) { 
    //custom field's click/touch event handler 
    CListItemField itemField = (CListItemField) field; 
    ScreenItemDetail scrDetail = new ScreenItemDetail(itemField.getModel()); 
    ScreenUtil.pushScreenWithLoader(scrDetail,true); 
} 

protected void onDisplay() { 
    super.onDisplay(); 
} 
} 

Answer 2

创建一个类像的下方。

import java.util.Vector; 
    import net.rim.device.api.collection.util.SparseList; 
    import net.rim.device.api.system.Bitmap; 
    import net.rim.device.api.ui.Color; 
    import net.rim.device.api.ui.Graphics; 
    import net.rim.device.api.ui.component.ListField; 
    import net.rim.device.api.ui.component.ListFieldCallback; 

    public class CListCallback implements ListFieldCallback { 
    private String[] resource; 
    private int rgb=Color.BLACK; 
    Vector elements; 
    Bitmap arraow; 
    public CListCallback(String[] resources){ 
     this.resource=resources; 

    } 
     public void drawListRow(ListField listField, Graphics graphics, int index, 
       int y, int width) { 

      String text=(String) get(listField, index); 
      graphics.setColor(rgb); 
      graphics.drawText(text,60,y+25); 
      graphics.drawLine(0, y+59, DConfig.disWidth, y+59); 

     } 
     public Object get(ListField listField, int index) { 

      return resource[index]; 
     } 
    public int getPreferredWidth(ListField listField) { 

      return DConfig.disWidth+10; 
     } 
    public int indexOfList(ListField listField, String prefix, int start) { 

      return -1; 
     } 

    } 

并在MainScreen类中使用上面的类。

CListCallback clmenu=new CListCallback(arrayitems); 
     final ListField lf = new ListField(arraymenu.length) { 
      protected boolean keyChar(char character, int status, int time) { 
       if (character == Keypad.KEY_ENTER) { 
        fieldChangeNotify(0); 
        return true; 
       } 
       return super.keyChar(character, status, time); 
      } 

      protected boolean navigationUnclick(int status, int time) { 
       fieldChangeNotify(0); 
       return true; 
      } 
     }; 
     lf.setCallback(clmenu); 
     lf.setRowHeight(60); 
     lf.setChangeListener(new FieldChangeListener() { 

      public void fieldChanged(Field field, int context) 
      { 
      int index=lf.getSelectedIndex(); 
           UiApplication.getUiApplication.pushScreen(newNewScreen(imgarray[index])); 
      } 
     }); 
     add(lf);  

那it.it将工作