编译OK，，但是运行保持，怎么回事呀？

Unable to create MIDlet HelloMidlet
java.lang.ClassNotFoundException: HelloMidlet
at com.sun.midp.midlet.MIDletState.createMIDlet(+29)
at com.sun.midp.midlet.Selector.run(+22) 


网上找到代码如下： 编译没有问题，，但是在虚拟机器上一运行，就报上面的错。怎么回事呢？


/*
 * HelloMidlet.java
  *
 * Created on 2007年1月26日, 下午12:34
 */
package hello;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
/**
 *
 * @author zhhz
 */
public class HelloMidlet extends MIDlet implements CommandListener {
    
    /** Creates a new instance of HelloMidlet */
    public HelloMidlet() {
    }
    
    private Form helloForm;                     
    private StringItem helloStringItem;
    private Command exitCommand;
    private Form form1;
    private Command exitCommand1;
    private ChoiceGroup choiceGroup1;
    private TextField textField1;
    private TextField textField2;
    private Command okCommand1;
    private Command cancelCommand1;
    private Command cancelCommand2;
    private Command okCommand2;
    private Command okCommand3;                   
    
                     
    /** This method initializes UI of the application.                        
     */
    private void initialize() {                      
        // Insert pre-init code here
        getDisplay().setCurrent(get_helloForm());                      
        // Insert post-init code here
    }                     
    
    /** Called by the system to indicate that a command has been invoked on a particular displayable.                      
     * @param command the Command that ws invoked
     * @param displayable the Displayable on which the command was invoked
     */
    public void commandAction(Command command, Displayable displayable) {                    
        // Insert global pre-action code here
        if (displayable == helloForm) {                     
            if (command == exitCommand) {                   
                // Insert pre-action code here
                getDisplay().setCurrent(get_form1());                       
                // Insert post-action code here
            }                      
        } else if (displayable == form1) {
            if (command == exitCommand1) {                    
                // Insert pre-action code here
                exitMIDlet();                       
                // Insert post-action code here
            } else if (command == okCommand3) {                     
               // = "/u8BF7/u8F93/u5165/u59D3/u540D/uFF1A"; // Insert pre-action code here
                // Do nothing                        
                // Insert post-action code here
            }                       
        }                     
        // Insert global post-action code here
}                   
    
    /**
     * This method should return an instance of the display.
     */
    public Display getDisplay() {                         
        return Display.getDisplay(this);
    }                        
    
    /**
     * This method should exit the midlet.
     */
    public void exitMIDlet() {                         
        getDisplay().setCurrent(null);
        destroyApp(true);
        notifyDestroyed();
    }                        
    
    /** This method returns instance for helloForm component and should be called instead of accessing helloForm field directly.                        
     * @return Instance for helloForm component
     */
    public Form get_helloForm() {
        if (helloForm == null) {                      
            // Insert pre-init code here
            helloForm = new Form(null, new Item[] {                       
                get_helloStringItem(),
                get_choiceGroup1()
            });
            helloForm.addCommand(get_exitCommand());
            helloForm.setCommandListener(this);                     
            // Insert post-init code here
        }                      
        return helloForm;
    }                    
    
    /** This method returns instance for helloStringItem component and should be called instead of accessing helloStringItem field directly.                        
     * @return Instance for helloStringItem component
     */
    public StringItem get_helloStringItem() {
        if (helloStringItem == null) {                      
            // Insert pre-init code here
            helloStringItem = new StringItem("Hello", "Hello, World!");                      
            // Insert post-init code here
        }                      
        return helloStringItem;
    }                    
    
    /** This method returns instance for exitCommand component and should be called instead of accessing exitCommand field directly.                        
     * @return Instance for exitCommand component
     */
    public Command get_exitCommand() {
        if (exitCommand == null) {                      
            // Insert pre-init code here
            exitCommand = new Command("NEXT", Command.EXIT, 1);                      
            // Insert post-init code here
        }                      
        return exitCommand;
    }                    
    /** This method returns instance for form1 component and should be called instead of accessing form1 field directly.                        
     * @return Instance for form1 component
     */
    public Form get_form1() {
        if (form1 == null) {                      
            // Insert pre-init code here
            form1 = new Form(null, new Item[] {                       
                get_textField1(),
                get_textField2()
            });
            form1.addCommand(get_exitCommand1());
            form1.addCommand(get_okCommand3());
            form1.setCommandListener(this);                     
            // Insert post-init code here
        }                      
        return form1;
    }                    
    /** This method returns instance for exitCommand1 component and should be called instead of accessing exitCommand1 field directly.                        
     * @return Instance for exitCommand1 component
     */
    public Command get_exitCommand1() {
        if (exitCommand1 == null) {                      
            // Insert pre-init code here
            exitCommand1 = new Command("exit", Command.EXIT, 1);                      
            // Insert post-init code here
        }                      
        return exitCommand1;
    }                    
    /** This method returns instance for choiceGroup1 component and should be called instead of accessing choiceGroup1 field directly.                         
     * @return Instance for choiceGroup1 component
     */
    public ChoiceGroup get_choiceGroup1() {
        if (choiceGroup1 == null) {                       
            // Insert pre-init code here
            choiceGroup1 = new ChoiceGroup("asdfasdfkasd;k f/ndsfasd/nf/nas/ndf/na/n/n", Choice.MULTIPLE, new String[0], new Image[0]);                        
            choiceGroup1.setSelectedFlags(new boolean[0]);                      
            // Insert post-init code here
        }                       
        return choiceGroup1;
    }                     
    /** This method returns instance for textField1 component and should be called instead of accessing textField1 field directly.                         
     * @return Instance for textField1 component
     */
    public TextField get_textField1() {
        if (textField1 == null) {                       
            // Insert pre-init code here
            textField1 = new TextField("/u8BF7/u8F93/u5165/u59D3/u540D/uFF1A", "", 120, TextField.ANY);                       
            // Insert post-init code here
        }                       
        return textField1;
    }                     
    /** This method returns instance for textField2 component and should be called instead of accessing textField2 field directly.                         
     * @return Instance for textField2 component
     */
    public TextField get_textField2() {
        if (textField2 == null) {                       
            // Insert pre-init code here
            textField2 = new TextField("/u8BF7/u8F93/u5165/u5BC6/u7801/uFF1A", null, 120, TextField.ANY);                       
            // Insert post-init code here
        }                       
        return textField2;
    }                     
    /** This method returns instance for okCommand1 component and should be called instead of accessing okCommand1 field directly.                         
     * @return Instance for okCommand1 component
     */
    public Command get_okCommand1() {
        if (okCommand1 == null) {                       
            // Insert pre-init code here
            okCommand1 = new Command("cancle", Command.OK, 1);                       
            // Insert post-init code here
        }                       
        return okCommand1;
    }