繼承問題，從繼承類的某些數據獲得NULL

我有兩個類。一個叫做另一個學生。學生繼承人。一切正常，直到我填寫我的表單並將數據傳遞到下一個表單進行顯示。繼承問題，從繼承類的某些數據獲得NULL

除了名稱，地址和狀態，一切都顯示正常。這些來自person類並具有NULL值。讓我瘋狂的是，城市，郵政編碼和出生日期來自同一個人班，工作得很好。我不明白爲什麼會發生這種情況，並希望有更多知識的人能指引我走向正確的方向。

這裏有2類：

public class Person 
{ 
    private string name; 
    private string address; 
    private string city; 
    private string state; 
    private string zipcode; 
    private DateTime birthdate; 

    public Person() 
    { 
    } 

    public Person(string name, string address, string city, string state, string zipcode, DateTime birthdate) 
    { 
     this.name = name; 
     this.address = address; 
     this.city = city; 
     this.state = state; 
     this.zipcode = zipcode; 
     this.birthdate = birthdate; 
    } 

    public string Name 
    { 
     get { return name; } 
     set { name = value; } 
    } 

    public string Address 
    { 
     get { return address; } 
     set { name = address; } 
    } 

    public string City 
    { 
     get { return city; } 
     set { city = value; } 
    } 
    public string State 
    { 
     get { return state; } 
     set { state = value; } 
    } 

    public string Zipcode 
    { 
     get { return zipcode; } 
     set { zipcode = value; } 
    } 

    public DateTime Birthdate 
    { 
     get { return birthdate; } 
     set { birthdate = value; } 
    } 
} 

public class Student : Person 
{ 
    private string studentID; 
    private double gradepointAverage; 
    private List<string> currentClasses = new List<string>(); 

    public Student() 
    { 
    } 

    public Student(string name, string address, string city, string state, string zipcode, DateTime birthdate, string studentID, double gradepointAverage, List<string> currentClasses) 
     : base(name, address, city, state, zipcode, birthdate) 
    { 
     this.studentID = studentID; 
     this.gradepointAverage = gradepointAverage; 
     this.currentClasses = currentClasses; 
    } 

    public string StudentID 
    { 
     get { return studentID; } 
     set { studentID = value; } 
    } 

    public double GradePointAverage 
    { 
     get { return gradepointAverage; } 
     set { gradepointAverage = value; } 
    } 

    public List<string> CurrentClasses 
    { 
     get { return currentClasses; } 
     set { currentClasses = value; } 
    } 
}

這裏就是我實例化類：

private void btnSave_Click(object sender, EventArgs e) 
    { 
     s = new Student(); 
     s.StudentID = txtStudentID.Text; 
     s.Name = txtName.Text; 
     s.Address = txtAddress.Text; 
     s.City = txtCity.Text; 
     s.State = txtState.Text; 
     s.Zipcode = txtZipCode.Text; 
     s.Birthdate = DateTime.Parse(txtBirthdate.Text); 
     s.GradePointAverage = Convert.ToDouble(txtGradPoint.Text); 


     string stringItmem; 
     foreach(Object selectedItem in lstClasses.SelectedItems) 
     { 
      stringItmem = selectedItem as String; 
      s.CurrentClasses.Add(stringItmem); 
     } 
     students.Add(s); 
     resetForm(); 
     MessageBox.Show("Student has been saved."); 
    }

來源

2013-12-10 Marc Usa

您正在使用哪個構造函數來實例'Student'？你是否使用具有所有參數的參數並將所有參數傳遞給基類？您是否嘗試設置斷點並調試應用程序？ –

我正在實例化學生，然後單獨設置它們。我使用了調試器，它在所有提到的字段中都顯示爲空。我決定打破將學生列入學生名單的地方，並且在那裏他們已經爲空。 –

因此，你的問題是你的學生的價值觀沒有從你的輸入中正確地設置（即值應該不是'null'），還是在下一個表單上顯示的是空值？對不起，你的問題不清楚你的問題到底是什麼。 – monty

public string Address 
{ 
    get { return address; } 
    set { name = address; } // Should be "address = value" 
}

看到二傳手 - 你這裏所做的是破壞你的name沒有設置address。這應該解釋你所有的數據損壞。由於您在代碼中首先設置了name，這解釋了爲什麼它們都是null。

來源

2013-12-10 03:15:36

是...複製/粘貼贏（丟失）再次:) – DRapp

當我沒有看到。談論沒有看到樹木與森林的方式。謝謝 –

與解決的問題是，在一組，你把它作爲name = address而不是address = value;

public string Address 
{ 
    get { return address; } 
    set { name = address; } 
}

來源

2013-12-10 03:15:51 Neaox

繼承問題，從繼承類的某些數據獲得NULL

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