ブラックベリーでカスタムドロップダウンを作成するには

Question

誰でもブラックベリー5.0に添付されているイメージに似たカスタムドロップダウンを作成できますか？私はオブジェクト選択フィールドを使用しましたが、それはラベルと共に来ています。カスタム作成ポップアップ画面を使用して、

Answer 1

私はカスタマイズしChoiceField作成した画像の下にショーとしてドロップダウンするために私を導きます。ここでは以下のコードサンプルは

package com.src.java.rim.ui; 

import net.rim.device.api.system.Bitmap; 
import net.rim.device.api.system.Display; 
import net.rim.device.api.ui.DrawStyle; 
import net.rim.device.api.ui.Field; 
import net.rim.device.api.ui.Graphics; 
import net.rim.device.api.ui.UiApplication; 
import net.rim.device.api.ui.XYEdges; 
import net.rim.device.api.ui.component.ListField; 
import net.rim.device.api.ui.component.ListFieldCallback; 
import net.rim.device.api.ui.container.HorizontalFieldManager; 
import net.rim.device.api.ui.container.PopupScreen; 
import net.rim.device.api.ui.container.VerticalFieldManager; 
import net.rim.device.api.ui.decor.BackgroundFactory; 
import net.rim.device.api.ui.decor.Border; 
import net.rim.device.api.ui.decor.BorderFactory; 

public class FWCustomChoiceField extends HorizontalFieldManager { 

    /*space between text and icon*/ 
    final int padding = 10; 

    String arrowBitmapName = "arrow_state_grey_right.png"; 

    Object choice[] = null; 

    int index = -1; 

    String text = "Please select one option"; 

    ListField choiceField = null; 
    public FWCustomChoiceField(final Object choice[]) { 

     this.choice = new Object[choice.length];   
     this.choice = choice; 

     choiceField = new ListField(){ 
      protected boolean navigationClick(int status, int time) { 

       Field focus = UiApplication.getUiApplication().getActiveScreen() .getLeafFieldWithFocus(); 

       if (focus instanceof ListField) { 
        ChoicePopupScreen popup = new ChoicePopupScreen(10, 80, choice); 
        popup.setChoice(choice);      
        UiApplication.getUiApplication().pushScreen(popup); 
       } 
       return super.navigationClick(status, time); 
       } 
     };  

     choiceField.setSize(1); 
     choiceField.setCallback(new TestListCallback()); 
     add(choiceField); 
    } 


    public void setSelIndex(int index){ 
     this.index = index; 
     this.text = choice[index].toString(); 
     choiceField.invalidate(); 
    } 

    public int getSelectedIndex(){ 
     return index; 
    } 

    final class TestListCallback implements ListFieldCallback { 
     TestListCallback() { 
     } 
     public void drawListRow(ListField list, Graphics g, int index, int y, int w) { 
      Bitmap bitmap = Bitmap.getBitmapResource(arrowBitmapName);   
      int fontWidth = getFont().getAdvance(text); 
      int width = Display.getWidth() ; 
      int posX = (width-(fontWidth + padding + bitmap.getWidth()))/2; 

      int height = list.getRowHeight(); 
      int posY = (height - bitmap.getHeight())/2; 

      g.drawText(text, posX, y, 0, w); 
      g.drawBitmap(posX+fontWidth+padding,posY, bitmap.getWidth(), bitmap.getHeight(), bitmap, 0, 0); 
     } 
     public Object get(ListField listField, int index) { 
      return null; 
     } 
     public int getPreferredWidth(ListField listField) { 
      return Graphics.getScreenWidth(); 
     } 
     public int indexOfList(ListField listField, String prefix, int start) { 
      return listField.indexOfList(prefix, start); 
     } 
    } 



    public class ChoicePopupScreen extends PopupScreen { 
     Object []choice = null; 

     /*holds the position for popup screen*/ 
     private int _posX = 0; 
     private int _posY = 0; 

     public ChoicePopupScreen(int posx,int posy, Object[] choice) { 
      /*calling super class constructor*/ 
      super(new VerticalFieldManager(), Field.FOCUSABLE); 

      this.setMargin(new XYEdges(1,1,1,1)); 

      this.choice = new Object[choice.length]; 
      this.choice = choice; 

      /*Setting position for popup screen*/ 
      _posX = posx; 
      _posY = posy; 

      /*list field customized to display as choice picker*/ 
      ListField choiceList = new ListField(){ 
       /*list field event handling using navigation click*/ 
       protected boolean navigationClick(int status, int time) { 
        /*getting the selected list index value*/ 
        int index = this.getSelectedIndex(); 

        /*returning the selected index to the main field*/ 
        setSelIndex(index); 

        /*removing the popup screen from the screen stack*/ 
        UiApplication.getUiApplication().popScreen(UiApplication.getUiApplication().getActiveScreen()); 

        /*required for event handling*/ 
        return super.navigationClick(status, time); 
       } 
      }; 

      /*displays the message when list is empty*/ 
      choiceList.setEmptyString("List is empty", DrawStyle.LEFT); 
      choiceList.setSize(choice.length); 
      choiceList.setCallback(new PopUpListCallback());    
      add(choiceList); 


      Border border = BorderFactory.createSimpleBorder(new XYEdges(), Border.STYLE_TRANSPARENT); 
      this.setBorder(border); 
     } 

     protected void setChoice(Object []choice) {    
      this.choice = new Object[choice.length]; 
      this.choice = choice; 
     } 

     protected void sublayout(int width, int height) { 
      super.sublayout(width, height);   
      /*setting the position for the popup screen*/ 
      setPosition(_posX , _posY); 
     } 
    } 

    private class PopUpListCallback implements ListFieldCallback { 
     PopUpListCallback() { 
     } 

     public void drawListRow(ListField list, Graphics g, int index, int y, int w) { 
      String text = choice[index].toString(); 
      g.drawText(text, padding, y, 0, w); 
     } 

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

     public int getPreferredWidth(ListField listField) { 
      return Graphics.getScreenWidth(); 
     } 

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

私はあなたがそのhttp://supportforums.blackberry.com/t5/Java-Developmentに類似したいと思います。このスレッドで

String choicestrs[] = {"Opt 1", "Opt 2", "Opt 3"}; 
add(new FWCustomChoiceField(choicestrs));