刚接触j2me，前来请教

[diqiure]

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

public class ChoiceGroupTest extends MIDlet
{
private Display display1;
private Form form;
private ChoiceGroup cg;
public ChoiceGroupTest()
{ display1=Display.getDisplay(this);
form=new Form("ChoiceGroupTest");
cg=new ChoiceGroup("请选择喜欢的编程语言：",Choice.EXCLUSIVE);
cg.append("c",null);cg.append("c++",null);cg.append("java",null);
);
form.append(cg);


}//构造函数
public void startApp() throws MIDletStateChangeException
{
display1.setCurrent(form);
}//程序开始时就运行这函数
public void pauseApp()
{
}//暂停函数
public void destroyApp(boolean unconditional)
{//notifyDestroyApp();
}//程序终止函数，并释放内存资源
}
提示：3410170 bytecodes executed
145 thread switches
1667 classes in the system (including system classes)
17743 dynamic objects allocated (529812 bytes)
1 garbage collections (0 bytes collected)
Uncaught exception java/lang/NoClassDefFoundError: ChoiceGrouptest.