Question

我正在制作一个带有声音效果的音板，我正在接受：

"A first chance exception of type 'System.NullReferenceException'" 
   when building after 'UI Task' (Managed): 
   Loaded 'Microsoft.Xna.Framework.dll'

我确实让它工作但是在更改之后（覆盖了以前的版本）我遇到了这个错误而且我被卡住了。 Java是我的第一语言，使用C＃我是初学者。我花了无数个小时寻找解决方案。

我认为nullReferenceException来自loadsound（）！我将声音文件（.wav）放在一个名为resources和build action的文件夹中：资源并复制到输出：不要复制（在这里尝试了所有选项）。另外在参考文献中引用了Microsoft.Xna.Framework

  using System;
using System.Collections.Generic;
using System.Linq;
using System.Net;
using System.Windows;
using System.Windows.Controls;
using System.Windows.Documents;
using System.Windows.Input;
using System.Windows.Media;
using System.Windows.Media.Animation;
using System.Windows.Resources;
using System.Windows.Shapes;
using Microsoft.Phone.Controls;
using Microsoft.Xna.Framework;
using Microsoft.Xna.Framework.Audio;
using Microsoft.Xna.Framework.Media;

namespace Craggy_Island
{
    public partial class MainPage : PhoneApplicationPage
    {
        // The Resources to play
        private SoundEffect drink;//(plus 23 more effects)

        // Flag that indicates if we need to resume Zune playback upon exiting.
        bool resumeMediaPlayerAfterDone = false;

        // Constructor
        public MainPage()
        {
            InitializeComponent();

            // Timer to simulate the XNA game loop (SoundEffect class is from the XNA Framework)
            GameTimer gameTimer = new GameTimer();
            gameTimer.UpdateInterval = TimeSpan.FromMilliseconds(33);

            // Call FrameworkDispatcher.Update to update the XNA Framework internals.
            gameTimer.Update += delegate { try { FrameworkDispatcher.Update(); } catch { } };

            // Start the GameTimer running.
            gameTimer.Start();

            // Prime the pump or we'll get an exception.
            FrameworkDispatcher.Update();

            //LoadSound("Resources/drink.wav", out drink);
            // Create and load SoundEffect objects.
            LoadSound("Resources/drink.wav", out drink);

        }

        private void LoadSound(String SoundFilePath, out SoundEffect Sound)
        {
            // For error checking, assume we'll fail to load the file.
            Sound = null;

            try
            {
                // Holds informations about a file stream.
                StreamResourceInfo SoundFileInfo = App.GetResourceStream(new Uri(SoundFilePath, UriKind.Relative));

                // Create the SoundEffect from the Stream
                Sound = SoundEffect.FromStream(SoundFileInfo.Stream);
            }
            catch (NullReferenceException)
            {
                // Display an error message
                MessageBox.Show("Couldn't load sound " + SoundFilePath);
            }
        }



        private void button_Click(object sender, RoutedEventArgs e)
        {
            Button Current = sender as Button;

            try
            {
                if (Current.Equals(button1))
                    drink.Play();//(other buttons here for other sound effects)



            }
            catch (NullReferenceException)
            {
                MessageBox.Show("Can't play, sound file problem.");
            }

        }
        #region Zune Pause/Resume

        private void ZunePause()
        {
            // Please see the MainPage() constructor above where the GameTimer object is created.
            // This enables the use of the XNA framework MediaPlayer class by pumping the XNA FrameworkDispatcher.

            // Pause the Zune player if it is already playing music.
            if (!MediaPlayer.GameHasControl)
            {
                MediaPlayer.Pause();
                resumeMediaPlayerAfterDone = true;
            }
        }

        private void ZuneResume()
        {
            // If Zune was playing music, resume playback
            if (resumeMediaPlayerAfterDone)
            {
                MediaPlayer.Resume();
            }
        }

        #endregion Zune Pause/Resume

    }
}

Answer 1

你正在采取艰难的方法。查看ContentManager（可从this.Content实例中访问Game）。您可以使用Content.Load<T>(string)访问音频文件，但是您需要将音频文件放在内容项目中。请勿更改其类型：将其保留为默认值。即使它不是一种资源，也不是它。它将被编译成不同的格式。另外，从传递给Content.Load<>的参数中省略文件扩展名。

Answer 2

除非您在Windows / Xbox上使用XNA进行游戏开发，否则请删除原始答案。（原始海报正在将它用于Zune。）

关于WAV文件：

首先，您需要将Copy to Output Directory设置为Copy if newer。（您可以使用Always，但这是不必要的。）

第二个问题是它的类型需要设置为Content。

Answer 3

在加载声音之前，您正在开始游戏：

gameTimer.Start();

FrameworkDispatcher.Update();

LoadSound("Resources/drink.wav", out drink);

Answer 4

我遇到了几乎相同的问题。最后我意外地得到了如下：

StreamResourceInfo streaminfo = Application.GetResourceStream(new Uri("project_name;component/folder_name/Sound3.wav", UriKind.RelativeOrAbsolute));
SoundEffect effect1 = SoundEffect.FromStream(streaminfo.Stream);
effect1.Play();

和：必须将.wav文件的“Build Action”属性设置为“Resource”，并将Porperty“Copy to Output Directory”设置为“Copy if newer”

顺便说一下，我正在使用Silverlight5。

nullReferenceException当我尝试播放音效？

4 个答案: