抛出TargetInvocationException c＃

Question

我有一个例程，要求后台工作人员完成。如下;

private void BatteryListFetchBackgroundWorkerRunWorkerCompleter(object sender, RunWorkerCompletedEventArgs e)
{
    this.Cursor = Cursors.Default;
    var sortedList = this.currentBatteries.Values.OrderBy(g => g, new BatteryNameComparer()); //breaks here

    this.BatteryBindingSource.DataSource = sortedList;
    if (this.batteryListBox.Items.Count > 0)
    {
        this.batteryListBox.SetSelected(0, true);
    }

    this.viewScheduleButton.Enabled = true;
    this.viewDefaultScheduleButton.Enabled = true;
    this.viewEditScheduleLimits.Enabled = true;
}

它突破的界线是;

                this.BatteryBindingSource.DataSource = sortedList;

异常是空引用异常，它在设置数据源时发生

BatteryNameComparer

的代码

 public class BatteryNameComparer : IComparer<Battery>
{
    /// <summary>
    /// Compares DDSMGroup 
    /// </summary>
    /// <param name="a">first value for comparison</param>
    /// <param name="b">second value for comparison</param>
    /// <returns>An integer indicating the compare result</returns>
    public int Compare(Battery a, Battery b)
    {
        int aId = int.Parse(a.DeviceName.Substring(BatteryOverviewControl.BatteryPrefixSubstring.Length));
        int bId = int.Parse(b.DeviceName.Substring(BatteryOverviewControl.BatteryPrefixSubstring.Length));

        return aId.CompareTo(bId);
    }
}

Answer 1

每当看到TargetInvocationException时，您应立即检查其InnerException属性以查找实际抛出的异常。

http://msdn.microsoft.com/en-us/library/system.exception.innerexception(v=vs.110).aspx

简单地说，TargetInvocationException只告诉你在某种调用上下文中抛出了另一个异常 - 这几乎总是一个跨线程操作或通过反射调用。