错误警报不会显示

Question

有人可以告诉我为什么当我输入错误的密码用户名时，下面的代码不会显示错误。由于

公共类LoginMIDlet扩展的MID​​let实现的CommandListener {

private boolean midletPaused = false; 
private Display display; 

//<editor-fold defaultstate="collapsed" desc=" Generated Fields ">      
private Form SignIn; 
private TextField userName; 
private TextField password; 
private StringItem sim_Result; 
private Form Continue; 
private Command _login; 
private Command _cancel; 
private Command okCommand; 
//</editor-fold>      

/** 
* The LoginMIDlet constructor. 
*/ 
public LoginMIDlet() { 
} 


public void validateUser(String user, String Password) { 
if (user.equals("N0203251") && Password.equals("DBTYPX")) { 
    switchDisplayable(null, getContinue()); 
} 

else { 
    switchDisplayable(null, getSignIn()); 
Alert error = new Alert("Login Incorrect", "Please try again", null, AlertType.ERROR); 
error.setTimeout(Alert.FOREVER); 
userName.setString(""); 
password.setString(""); 
display.setCurrent(error); 
} 

}

Answer 1

在 “其他”：

switchDisplayable(null, getSignIn()); 

也许此行不允许过程达到“警报“行。

祝你好运！