Question

我使用Dr.WPF的ObservableDictionary类，我需要序列化和反序列化这个集合。序列化进展顺利，但是当我尝试反序列化时抛出异常：

$exception  {"Object reference not set to an instance of an object."}   System.Exception {System.NullReferenceException}
StackTrace  "   at EngineConfigurationManager.ObservableDictionary.ObservableDictionary`2.AddEntry(TKey key, TValue value) in d:\\Доки\\Editor\\EngineConfigurationManager\\EngineConfigurationManager\\ObservableDictionary\\ObservableDictionary.cs:line 196\r\n   at EngineConfigurationManager.ObservableDictionary.ObservableDictionary`2.OnDeserialization(Object sender) in d:\\Доки\\Editor\\EngineConfigurationManager\\EngineConfigurationManager\\ObservableDictionary\\ObservableDictionary.cs:line 592\r\n   at System.Runtime.Serialization.ObjectManager.RaiseDeserializationEvent()\r\n   at System.Runtime.Serialization.Formatters.Binary.ObjectReader.Deserialize(HeaderHandler handler, __BinaryParser serParser, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage)\r\n   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream, HeaderHandler handler, Boolean fCheck, Boolean isCrossAppDomain, IMethodCallMessage methodCallMessage)\r\n   at System.Runtime.Serialization.Formatters.Binary.BinaryFormatter.Deserialize(Stream serializationStream)\r\n   at EngineConfigurationManager.ConfigClasses.Camera.CameraConfigurationManager.Load() in d:\\Доки\\Editor\\EngineConfigurationManager\\EngineConfigurationManager\\ConfigClasses\\Camera\\CameraConfigurationManager.cs:line 936" string

我尝试调试提到的方法

public virtual void OnDeserialization(object sender)
    {
        if (_siInfo != null)
        {
            Collection<DictionaryEntry> entries = (Collection<DictionaryEntry>)
                _siInfo.GetValue("entries", typeof(Collection<DictionaryEntry>));
            foreach (DictionaryEntry entry in entries)
                AddEntry((TKey)entry.Key, (TValue)entry.Value);
        }
    }

protected KeyedDictionaryEntryCollection<TKey> _keyedEntryCollection;

protected virtual bool AddEntry(TKey key, TValue value)
    {
        _keyedEntryCollection.Add(new DictionaryEntry(key, value));
        return true;
    }

但我找不到任何错误：键和值不为空或为空。

有谁知道问题的原因是什么？

修改 ObservableDictionary类中的构造函数很少，但我认为反序列化不会调用它们中的任何一个。

public ObservableDictionary()
    {
        _keyedEntryCollection = new KeyedDictionaryEntryCollection<TKey>();
    }

    public ObservableDictionary(IDictionary<TKey, TValue> dictionary)
    {
        _keyedEntryCollection = new KeyedDictionaryEntryCollection<TKey>();

        foreach (KeyValuePair<TKey, TValue> entry in dictionary)
            DoAddEntry((TKey)entry.Key, (TValue)entry.Value);
    }

    public ObservableDictionary(IEqualityComparer<TKey> comparer)
    {
        _keyedEntryCollection = new KeyedDictionaryEntryCollection<TKey>(comparer);
    }

    public ObservableDictionary(IDictionary<TKey, TValue> dictionary, IEqualityComparer<TKey> comparer)
    {
        _keyedEntryCollection = new KeyedDictionaryEntryCollection<TKey>(comparer);

        foreach (KeyValuePair<TKey, TValue> entry in dictionary)
            DoAddEntry((TKey)entry.Key, (TValue)entry.Value);
    }

我可以这样做：

protected KeyedDictionaryEntryCollection<TKey> _keyedEntryCollection = new        KeyedDictionaryEntryCollection<TKey>();

但我不认为这是正确的方法。我以这种方式反序列化集合： CombinedCameraContainer =（ObservableDictionary）binaryFormatter.Deserialize（fs）;

在这种情况下，你有什么建议吗？

Answer 1

根据您的评论，这是抛出异常的行：

_keyedEntryCollection.Add(new DictionaryEntry(key, value));

该行中取消引用的唯一引用是_keyedEntryCollection，因此必须为null。

要解决您的问题，您需要在构造实例时初始化_keyedEntryCollection字段：

protected KeyedDictionaryEntryCollection<TKey> _keyedEntryCollection
  = new KeyedDictionaryEntryCollection<TKey>();

或者您可以在适当的构造函数中执行初始化。

Answer 2

问题是ObservableDictionary最有可能使用KeyValuePair作为其基础项类型。此类是不可变的，因此无法使用无参数构造函数构造它，然后设置其Key和Value成员。因此，它不能与大多数期望这种行为的反序列化器一起使用。

无法反序列化ObservableDictionary

2 个答案: