在這種情況下，Rethrow是一個例外

Question

我有這樣的事情：

public byte[] AnyMethod(){

  try {
    ...
  }
  catch (Exception e) {
    string errorMessage = 
      "Some custom message, which should the caller of that method should receive";

    // I thought something of this ,to pass through my custom exception to the caller?!
    throw new ApplicationException(errorMessage);

    //but this does not allow the method
  }

}

但是這個：

throw new ApplicationException(errorMessage);

將導致：

在... dll中發生了'System.ApplicationException'類型的異常，但未在用戶代碼中處理

怎么做自定義errror消息給我上面提到的方法的調用者？

Answer 1

首先，使用自定義異常或至少一個更有意義的異常而不是ApplicationException 。 其次，如果你的方法拋出它，你必須捕獲異常。

所以調用方法也應該在try...catch包裝方法調用：

try
{
    byte[] result = AnyMethod();
}catch(MyCustomException ex)
{
    // here you can access all properties of this exception, you could also add new properties
    Console.WriteLine(ex.Message);
}
catch(Exception otherEx)
{
    // all other exceptions, do something useful like logging here
    throw;  // better than throw otherEx since it keeps the original stacktrace 
}

這是一個抽象的簡化示例：

public class MyCustomException : Exception
{
    public MyCustomException(string msg) : base(msg)
    {
    }
}

public byte[] AnyMethod()
{
    try
    {
        return GetBytes(); // exception possible
    }
    catch (Exception e)
    {
        string errorMessage = "Some custom message, which should the caller of that method should receive";
        throw new MyCustomException(errorMessage);
    }
}

但請注意，不應將異常用於正常的程序流程。 相反，您可以返回true或false以指示操作是否成功，或者使用out byte[]的out參數 ，如int.TryParse （或其他TryParse方法）。

Answer 2

publy byte[] AnyMethod(){

try{


}catch(Exception e){

    string errorMessage = string.Format("Some custom message, which should the caller of that method should receive. {0}", e);

    //I thought something of this ,to pass through my custom exception to the caller?!
    throw new ApplicationException(errorMessage);
    //but this does not allow the method
    }

    }

要么

public byte[] AnyMethod(){

try{


}catch(Exception e){

string errorMessage = "Some custom message, which should the caller of that method should receive";

//I thought something of this ,to pass through my custom exception to the caller?!
throw new ApplicationException(errorMessage, e);
//but this does not allow the method
}

}