如何修复 Xamarin 'System.ArgumentNullException：'值不能为空。 参数名称：地址'异常

Question

When building and running the Application I get a 'System.ArgumentNullException: 'Value cannot be null. Parameter name: address' Exception.

The Exception Points to this section of code, to line where the Endpoint is initialized:

public void sendInstruction(string instruction)
    {
        char[] charInput = instruction.ToCharArray();
        Byte[] sendBytes = Encoding.ASCII.GetBytes(charInput);
        IPEndPoint epWK = new IPEndPoint(ip, port);
        udp.Send(sendBytes, sendBytes.Length, epWK);
    }

All Parameters are defined before:

public IPAddress ip;
public int port;
UdpClient udp = new UdpClient();

And set:

ip = IPAddress.Parse("192.168.178.62");
port = 54490;

The code worked before so I don't understand why this exception triggers.

Answer 1

可能在调用 sendInstruction 之前没有调用初始化 ip 的代码。