如何在第一个方法处于运行状态时调用另一个方法

Question

我正在开发一个控制台应用程序，其中编写了两个方法start和stop。当调用start方法时，它开始从系统捕获音频数据并保持工作状态，并且控制台卡在一个点上。现在我想调用stop方法来停止start方法，但是控制台仍然停留在start方法上。我尝试从另一个控制台调用stop方法，但它失败了：“未处理的异常：System.NullReferenceException：对象引用未设置为对象的实例。” 我怎么能做到这一点？

首先，我想打电话给wavtomp3，当我正在工作时，我想从控制台应用调用stoprecording()。 这是我的代码：

    static LameMP3FileWriter wri;
    static IWaveIn waveIn;

    public void wavtomp3(string fName,string storageLocation)
    {

        string[] aFileName=fName.Split('.');
        aFileName[0] = aFileName[0] + ".mp3";
        string aSaveLocation = storageLocation + "\\"+aFileName[0];

       // MessageBox.Show("Sample Rate=" + waveIn.WaveFormat.SampleRate.ToString());
       // string fname = DateTime.Now.Ticks.ToString();

        // Start recording from loopback
        waveIn = new WasapiLoopbackCapture();
        wri = new LameMP3FileWriter(aSaveLocation, waveIn.WaveFormat, 44);
        waveIn.DataAvailable += waveIn_DataAvailable;
        waveIn.RecordingStopped += waveIn_RecordingStopped;
        waveIn.StartRecording();
    }

    static void waveIn_RecordingStopped(object sender, StoppedEventArgs e)
    {
        if (waveIn != null) // working around problem with double raising of RecordingStopped
        {
            waveIn.Dispose();
            waveIn = null;
        }
        if (wri != null)
        {
            wri.Close();
            wri = null;
        }

    }

    static void waveIn_DataAvailable(object sender, WaveInEventArgs e)
    {
        if (wri != null)

            if (e.BytesRecorded == 0)
            {
                wri.Write(e.Buffer, 0, 12800);
                Debug.WriteLine("Adding Silence To File No Sound is playing");
            }
            else if (e.BytesRecorded > 0)
            {
                wri.Write(e.Buffer, 0, e.BytesRecorded);
                Debug.WriteLine("Sound Playing From Sound Card and recording");
            }

        Debug.WriteLine("bytes record=" + e.BytesRecorded);

    }

    public void stoprecording()
    {

        waveIn.StopRecording();
        Debug.WriteLine("StopRecording");

    }