c# - 无法从列表中读取帐号(Cannot read account number from list)

Question

I am trying to read AccountNumber from a text file, but it does not seem to be reading the AccountNumber from the text file, and I can confirm that the text file location string is correct.

(我正在尝试从文本文件中读取AccountNumber，但似乎没有从文本文件中读取AccountNumber，因此我可以确认文本文件位置字符串正确。)

Also, note that currently the user is only set to access BasicAccountTestRepository class, but I am trying to get the LoadAccounts method to be able to call GetAccounts() from FileAccountRepository.cs.

(另外，请注意，当前仅将用户设置为访问BasicAccountTestRepository类，但是我正在尝试获取LoadAccounts方法，以便能够从FileAccountRepository.cs调用GetAccounts（）。)

According to my instructions, I should be able to read from the text file in this class.

(根据我的指示，我应该能够从此类中的文本文件中进行读取。)

I am getting a NullReferenceException on LoadAccounts method, says "Object reference not set to an instance of an object."

(我在LoadAccounts方法上收到NullReferenceException，说“对象引用未设置为对象的实例”。)

Accounts.txt

(Accounts.txt)

AccountNumber,Name,Balance,Type
10001,Free Account,100,F
20002,Basic Account,500,B
30003,Premium Account,1000,P

FileAccountRepository.cs

(FileAccountRepository.cs)

public class FileAccountRepository : IAccountRepository
{
    List<Account> accounts = new List<Account>();
    public Account _account = new Account();

    public void GetUsers() {
        string path = @".Accounts.txt";
        string[] rows = File.ReadAllLines(path);


        for (int i = 1; i < rows.Length; i++)
        {
            string[] columns = rows[i].Split(',');

            //Account account = new Account();
            _account.AccountNumber = columns[0];
            _account.Name = columns[1];
            _account.Balance = Decimal.Parse(columns[2]);
            if (columns[3] == "F")
            {
                _account.Type = AccountType.Free;
            }
            else if (columns[3] == "B")
            {
                _account.Type = AccountType.Basic;
            }
            else if (columns[3] == "P")
            {
                _account.Type = AccountType.Premium;
            }

            accounts.Add(_account);
        }
    }


    public Account LoadAccount(string AccountNumber)
    {            
        if (accounts.Any(x => x.AccountNumber == AccountNumber))
        {
            return _account;
        }

        return null;
    }

    public void SaveAccount(Account account)
    {
        _account = account;
    }        
}

AccountManager.cs

(AccountManager.cs)

...
public AccountLookupResponse LookupAccount(string accountNumber)
    {
        AccountLookupResponse response = new AccountLookupResponse();
        FileAccountRepository fileAccount = new FileAccountRepository(); //NullReferenceException

        fileAccount.GetUsers();
        response.Account = _accountRepository.LoadAccount(accountNumber);

        if(response.Account == null)
        {
            response.Success = false;
            response.Message = $"{accountNumber} is not a valid account.";
        }
        else
        {
            response.Success = true;
        }

        return response;
    }
...

  ask by Alejandro H translate from so

Answer 1

等待大神答复