4

编辑：这个问题已经解决，非常感谢 Reniuz 5 小时的工作和对这个问题的研究，谢谢大家。

NullReferenceException：对象引用未设置为对象的实例。在下面的代码上，我已经搜索了 7 到 8 个小时，现在试图修复它。

private void buttonAddEffect_Click_1(object sender, EventArgs e)
{
    EffectSelectorForm effectSelectorForm = new EffectSelectorForm(Effects);
    if (effectSelectorForm.ShowDialog(this) == DialogResult.OK)
    {
        // create a new instance of the selected effect as we may want multiple copies of one effect
        Effect effect = (Effect)Activator.CreateInstance(effectSelectorForm.SelectedEffect.GetType());
        audioGraph.AddEffect(effect);
        int index = checkedListBox1.Items.Add(effect, true);
        checkedListBox1.SelectedIndex = index;
    }
    //MessageBox.Show(String.Format("I have {0} effects", Effects.Count));
}

错误就行了： EffectSelectorForm effectSelectorForm = new EffectSelectorForm(Effects);

班上：

namespace WindowsFormsApplication13
{
    public partial class EffectSelectorForm : Form
    {
        public EffectSelectorForm(ICollection<Effect> effects)
        {
            InitializeComponent();
            listBoxEffects.DisplayMember = "Name";
            listBoxEffects.DataSource = effects;
        }

        private void buttonOK_Click(object sender, EventArgs e)
        {
            this.DialogResult = DialogResult.OK;
            this.Close();
        }

        public Effect SelectedEffect
        {
            get
            {
                return (Effect)listBoxEffects.SelectedItem;
            }
        }

        private void listBoxEffects_DoubleClick(object sender, EventArgs e)
        {
            buttonOK_Click(sender, e);
        }

这应该做的是当 effectSelectorForm 加载时，它应该列出所有语音转换器选项，但它不这样做....并重新编写了大约 400 行代码以使其在我的应用程序中运行，但现在我遇到了这个问题，我并没有放弃到目前为止所做的所有努力。如果它加载到另一个项目中，为什么不在这个项目中？我一遍又一遍地检查代码几个小时，并认为我错过了一些东西，但没有。

任何帮助都会很棒。

堆

See the end of this message for details on invoking 
just-in-time (JIT) debugging instead of this dialog box.

************** Exception Text **************
System.NullReferenceException: Object reference not set to an instance of an object.
   at WindowsFormsApplication13.pwn4g3.buttonAddEffect_Click_1(Object sender, EventArgs e) in F:\Users\Tom\Desktop\New folder\New folder (2)\TestApp\pwn4g3\PWN4G3\MainForm2.cs:line 1758
   at System.Windows.Forms.Control.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnClick(EventArgs e)
   at System.Windows.Forms.Button.OnMouseUp(MouseEventArgs mevent)
   at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
   at System.Windows.Forms.Control.WndProc(Message& m)
   at System.Windows.Forms.ButtonBase.WndProc(Message& m)
   at System.Windows.Forms.Button.WndProc(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
   at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
   at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)

效果.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace JSNet
{    

    public abstract class Effect
    {
        private List<Slider> sliders;
        public float SampleRate { get; set; }
        public float Tempo { get; set; }
        public bool Enabled { get; set; }

        public Effect()
        {
            sliders = new List<Slider>();
            Enabled = true;
            Tempo = 120;
            SampleRate = 44100;
        }

        public IList<Slider> Sliders { get { return sliders; } }

        public Slider AddSlider(float defaultValue, float minimum, float maximum, float increment, string description)
        {
            Slider slider = new Slider(defaultValue, minimum, maximum, increment, description);
            sliders.Add(slider);
            return slider;
        }

        public abstract string Name { get; }

        // helper base methods
        // these are primarily to enable derived classes to use a similar
        // syntax to JS effects
        protected float slider1 { get { return sliders[0].Value; } }
        protected float slider2 { get { return sliders[1].Value; } }
        protected float slider3 { get { return sliders[2].Value; } }
        protected float slider4 { get { return sliders[3].Value; } }
        protected float slider5 { get { return sliders[4].Value; } }
        protected float slider6 { get { return sliders[5].Value; } }
        protected float slider7 { get { return sliders[6].Value; } }
        protected float slider8 { get { return sliders[7].Value; } }
        protected float min(float a, float b) { return Math.Min(a, b); }
        protected float max(float a, float b) { return Math.Max(a, b); }
        protected float abs(float a) { return Math.Abs(a); }
        protected float exp(float a) { return (float)Math.Exp(a); }
        protected float sqrt(float a) { return (float)Math.Sqrt(a); }
        protected float sin(float a) { return (float)Math.Sin(a); }
        protected float tan(float a) { return (float)Math.Tan(a); }
        protected float cos(float a) { return (float)Math.Cos(a); }
        protected float pow(float a, float b) { return (float)Math.Pow(a, b); }
        protected float sign(float a) { return Math.Sign(a); }
        protected float log(float a) { return (float)Math.Log(a); }
        protected float PI { get { return (float)Math.PI; } }

        protected void convolve_c(float[] buffer1, int offset1, float[] buffer2, int offset2, int count)
        {
            for (int i = 0; i < count * 2; i += 2)
            {
                float r = buffer1[offset1 + i];
                float im = buffer1[offset1 + i + 1];
                float cr = buffer2[offset2 + i];
                float ci = buffer2[offset2 + i + 1];
                buffer1[offset1 + i] = r * cr - im * ci;
                buffer1[offset1 + i + 1] = r * ci + im * cr;
            }
        }


        public virtual void Init()
        {
        }


        public abstract void Slider();


        public virtual void Block(int samplesblock)
        { 
        }


        public abstract void Sample(ref float spl0, ref float spl1);

        public override string ToString()
        {
            return Name;
        }
    }
}
4

4 回答 4

3

如果问题在这里是 100%

EffectSelectorForm effectSelectorForm = new EffectSelectorForm(Effects);

只有一种可能的解释：属性/变量“效果”未正确初始化...调试代码以查看传递给对象的内容。

几个小时后编辑

有一些问题：

  • MEF 属性 [Import] 没有按预期工作，因此我们暂时将其替换为手动填充的 List<>。当集合为空时，它会导致代码稍后出现异常，当方法尝试获取所选项目的类型但没有时。

  • 几个事件处理程序没有连接到控制事件

一些问题仍然存在，但我相信 OP 的原始问题已得到解决。其他问题与此无关。

于 2012-04-06T12:12:58.840 回答
0

在调试期间，中断所有抛出的异常。调试->异常

检查所有“抛出”异常。F5，代码将停在违规行。

于 2012-04-06T14:21:08.587 回答
0

我有同样的问题，但它只发生在 Godaddy 的已发布网站上。在我的本地主机中没有问题。

该错误来自我试图为标签分配值的 aspx.cs（代码隐藏文件）。从后面的代码中看来，标签 Text 似乎为空。所以我所做的只是将 ASPX 文件中的所有标签文本属性从 Text="" 更改为 Text=""。

问题消失了。我不知道为什么托管版本会发生错误，但不会在我的本地主机上发生错误，也没有时间找出原因。但它现在工作正常。

于 2012-11-17T00:57:35.480 回答
0

I was getting this same error, but for me this was due to a method in a base class (in Project A) having the output type changed from a non-void type to void. A child class existed in Project B (which I didn't want used and had marked obsolete) that I missed when performing this update and hence started throwing this error.

1>CSC : error CS8104: An error occurred while writing the output file: System.NullReferenceException: Object reference not set to an instance of an object.

Original Code: 

[Obsolete("Calling this method will throw an error")]
public override CompletionStatus Run()
{
    throw new CustomException("Run process not supported.");
}

Revised Code: 

[Obsolete("Calling this method will throw an error")]
public override void Run()
{
    throw new CustomException("Run process not supported.");
}
于 2020-06-18T11:34:03.123 回答