向文本框添加值将转到异常"object reference not set to an instance of an object"

Question

我正在进行一个.NET项目，在该项目中，我应该从web服务获取数据，然后在telerik报告中显示这些数据。问题是，我的代码转到异常"对象引用未设置为对象实例">

public CertifikatePersonale(string ssn)
{
string COUNTY = null;
string FATHER_NAME = null;
try
{
ArrayList list = new ArrayList();
SkyServices service = new SkyServices();
object [] merrcertifikate = getPerCertificate(ssn);
for (int i = 0; i < merrcertifikate.Length; i++)
{
string SSN = ((string)(merrcertifikate[1]));
string LAST_NAME = ((string)(merrcertifikate[2]));
FATHER_NAME = ((string)(merrcertifikate[3]));
string ADDRESS = ((string)(merrcertifikate[4]));
string GENDER = ((string)(merrcertifikate[5]));
string BIRTH_PLACE = ((string)(merrcertifikate[6]));
string BIRTH_DATE = ((string)(merrcertifikate[7]));
string MOTHER_NAME = ((string)(merrcertifikate[8]));
string MARITAL_STATUS = ((string)(merrcertifikate[9]));
COUNTY = ((string)(merrcertifikate[10]));
string DOCUMENT_TYPE = ((string)(merrcertifikate[11]));
string DOCUMENT_ISSUE_DATE = ((string)(merrcertifikate[12]));
string DOCUMENT_EXPIRATION_DATE = ((string)(merrcertifikate[13]));
string RESPONSE = ((string)(merrcertifikate[14]));
string RESPONSE_DATA = ((string)(merrcertifikate[15]));
}
txb_Nation.Value = COUNTY.ToString().ToUpper();
}
catch { }
}

行

txb_Nation.Value = COUNTY.ToString().ToUpper();  

导致例外，即使郡有价值。请帮忙，这比应该花的时间还多。谢谢

Answer 1

如果COUNTY真的有一个值，那么它必须是未初始化的txb_Nation。您的代码没有显示引用的来源；检查其值是否设置正确。

Answer 2

试试这个：

txb_Nation.Value = COUNTY==null?"":COUNTY.ToString().ToUpper();