Question

这就是我想要做的事情：

 private void btnOk_Click(object sender, EventArgs e)
    {
        string login = loginTextBox.Text;
        string password = passwordtextBox.Text;

        myLogin m = new myLogin(login, password);

        **if (m.getX != "" && m.getY != "")**
        {
             displayLabel.Text = "The information entered is:";
             resultLogin.Text =
             "Login: " + m.getX();
             resultPassword.Text =
             "Password: " + m.getY();
             } // end if
         else
           displayLabel.Text = "Enter information above";
         } // end method OkButton_Click

问题在于代码被＆＃34; **＆＃34;包围。有没有办法检查文本框是否为空而没有收到错误？

编辑：

myLogin看起来像这样：

 public class myLogin 
{
    private readonly string login, password;
    public myLogin(string x, string y)
    {
        login = x;
        password = y;
    }

    public string getX()
    {
        return login;
    }

    public string getY()
    {

        return password;
    }

Answer 1

您希望调用方法并比较其结果：

 if (m.getX() != "" && m.getY() != "") ...

作为进一步改进，您可能希望将方法重构为属性：

 //TODO: think on changing name "X" to "Login" 
 public string X { 
   get {
     return login;
   }
 } 

 //TODO: think on changing name "X" to "Password" 
 public string Y { 
   get {
     return password;
   }
 }

完成此操作后，您可以轻松完成

if (X != "" && Y != "") ...

最后，只需将登录/密码验证的所有逻辑移到自己的类中：

// This class holds login/password: so it's it that responsible for validation
public class MyLogin() {
  public MyLogin(string login, string password) {
    if (null == login)
      throw new ArgumentNullException("login"); 
    else if (null == password)
      throw new ArgumentNullException("password"); 

    Login = login;
    Password = password; 
  }

  // Property with a readble name (what's X?)
  public string Login {
    get;
    private set;
  }

  // Property with a readble name (what's Y?)
  public string Password {
    get;
    private set;
  }

  public bool IsValid {
    get {
      return !string.IsNullOrEmpty(Login) &&
             !string.IsNullOrEmpty(Password); 
    }
  }
}

请注意现在如何轻松工作：

private void btnOk_Click(object sender, EventArgs e) {
  MyLogin m = new myLogin(loginTextBox.Text, passwordtextBox.Text);

  if (m.IsValid) 
  {
      displayLabel.Text = "The information entered is:";  
      resultLogin.Text = $"Login: {m.Login}";
      resultPassword.Text = $"Password: {m.Password}";
  }
  else 
      displayLabel.Text = "Enter information above";
}

接线员＆＃39;！=＆＃39;不能应用于类型＆＃39;方法组的操作数＆＃39;和＆＃39;字符串＆＃39;

1 个答案: