C# 检查 ref List<> 内容是否改变

Question

例如我在 class:

中有这个

List<int> myIntegerList;

public MyClass(ref List<int> intList)
{
    myIntegerList= intList;
}

这是我的主要 class:

List<int> myIntegerList = new List<int>();
MyClass myNewClass;

for (int i = 0; i < 10; i++)
{
    myIntegerList .Add(Random.Next(0, 100));
}

myNewClass = new MyClass(ref IntegerList);

如果引用的 List<int> 的内容发生变化，是否有一种简单的方法可以检查 myNewClass 对象？例如如果列表中的任何随机整数发生变化，则在 myNewClass 对象中引发一个事件。

Answer 1

使用 ObservableCollection..查看下面的内容link 以获得进一步的参考

ObservableCollection msdn

Answer 2

List<T> 不会那样做，但 ObservableCollection<T> 会。另外，不要在构造函数中使用 ref 参数；任何引用 class 实例的 C# 变量都已经是一个引用。 class 类型的 ref 参数是一个引用到一个引用，这是你不想要的，可能也不想考虑。

using System.Collections.ObjectModel;

public class MyClass
{
    private ObservableCollection<int> _integerList;

    //  Do not make this a ref parameter, it's a reference already
    public MyClass(ObservableCollection<int> intList)
    {
        _integerList = intList;
        _integerList.CollectionChanged += _integerList_CollectionChanged;
    }

    private void _integerList_CollectionChanged(object sender, System.Collections.Specialized.NotifyCollectionChangedEventArgs e)
    {
        //  Do stuff here in response to changed values in the list. 

        //  Now back to the reference thing again: int is immutable.
        //  You can't change it, you can only replace it with another 
        //  int. This event will be raised when you do that. 
        //
        //  If the objects in the ObservableCollection are class 
        //  instances rather than ints, they're mutable. You can 
        //  change their properties without replacing them. 
        //  ObservableCollection cannot know when that happens, so 
        //  it can't tell you. 
        //
        //  In that case, you'd need the class to implement 
        //  INotifyPropertyChanged. That's a different can of worms, 
        //  but it's a manageable one. 
    }
}

...

ObservableCollection<int> ints = new ObservableCollection<int>();
MyClass myNewClass;
var r = new Random();

for (int i = 0; i < 10; i++)
{
    ints.Add(r.Next(0, 100));
}

myNewClass = new MyClass(ints);

C# 检查 ref List<> 内容是否改变

C# check if ref List<> contents have changed

c#

events

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ref