如何从C＃中的Object []中删除特定类型的变量

Question

I have an array of Objects type which have information of variable of different classes, say, ClassA and ClassB .

public object[] SelectedObjects { get; }

Now I am filtering the objects of ClassB which I need to remove from the array of SelectedObjects .

var selectedClassBObjects = SelectedObjects.OfType<ClassB>().ToList();

When I perform the operation of Remove() or RemoveAll() , it does not do anything .

Can anyone suggest me how to perform this operation?

I need to remove objects of ClassB because at a time only one object of ClassB can be present when user is trying to Highlight the objects on the canvas. First remove the ClassB objects then add the newly selected ClassB objects to SelectedObjects[] .

Answer 1

You can't remove anything from an array, you will need to create a new one. If you want to exclude objects of type ClassB you can do:

SelectedObjects = SelectedObjects.Where(x => !(x is ClassB)).ToArray();

If you want a modifiable collection, List<T> is a better choice than an array.

Answer 2

If you insist on array you can put the backing field explicitly:

private object[] m_SelectedObjects = new object[0];

public object[] SelectedObjects {
  get {
    return m_SelectedObjects;
  }
}

private void MyRemove() {
  // We can't modify read-only property but can operate with its backing field 
  m_SelectedObjects = m_SelectedObjects?.OfType<ClassB>()?.ToArray();
}

Another possibility is to change array object[] into List<object> :

public List<object> SelectedObjects { get; }

...

// We still can't assign SelectedObjects but we can modify the collection now
SelectedObjects?.RemoveAll(item => !(item is TypeB));