J2ME学习笔记：ChoiceGroup的使用，附代码（原创）

ChoiceGroup的功能与List相近，只不过是多了个Item控件，其构造方法：ChoiceGroup（标题，类型，String[],Image[]），在此程序中有个值得主题的地方：textfield.setString(group.getString(group.getSelectedIndex())); ，此句group.getSelectedIndex（）取得group第几个内容，然后group.getString转成文字并且textfield.setString显示出来，够详细了吧呵呵，以下给出完整程序：

import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
import javax.microedition.lcdui.*;

public class ChoiceGroupDemo extends MIDlet implements CommandListener,ItemStateListener {

private Command exitCommand = new Command("Eixt",Command.EXIT,1);
private Display display;
private Form mainForm;
private TextField textfield;
private ChoiceGroup group;

public ChoiceGroupDemo() {

   mainForm = new Form("Choice Group");
                                       //图片数组
   Image[] imageArray = null;
  
   try{
    Image icon = Image.createImage("/1.png");
    imageArray = new Image[]{icon,icon,icon,icon};
   }catch(java.io.IOException err){System.out.println("Image err...");}
  
   String[] stringArray ={"选项A","选项B","选项C","选项D"};
                                                        //创建Pop-Up类型
   group = new ChoiceGroup("Pop-Up",ChoiceGroup.POPUP,stringArray,imageArray);
   textfield = new TextField("当前的选项为：","选项A",20,TextField.ANY);
                                                  //可以添加控件了
   mainForm.append(group);
   mainForm.append(textfield);
   mainForm.addCommand(exitCommand);
   mainForm.setCommandListener(this);
   mainForm.setItemStateListener(this);   //设置了监听器
}

protected void destroyApp(boolean arg0) throws MIDletStateChangeException {
  
  

}

 

public void commandAction(Command c, Displayable d) {         //处理Command事件

   if(c == exitCommand)
   {
    try {
     destroyApp(false);
    } catch (MIDletStateChangeException e) {
     // TODO Auto-generated catch block
     e.printStackTrace();
    }
    notifyDestroyed();
   }
  
}

public void itemStateChanged(Item item) {
   if (item instanceof ChoiceGroup)
   {
    textfield.setString(group.getString(group.getSelectedIndex())); //本程序重点！取得并更新内容
    /*TextBox tb = new TextBox("new","superise",15,0);
    display.setCurrent(tb);*/ //这个是可以触发屏幕的更新
   }
  
  
}

protected void pauseApp() {
  

}

protected void startApp() throws MIDletStateChangeException {
  
   display = Display.getDisplay(this);
   display.setCurrent(mainForm);
  

}

}