How to remove variable of Specific Type from Object in C#

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

Objects

ClassA

ClassB

public object SelectedObjects get;


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

ClassB

SelectedObjects

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


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

Remove()

RemoveAll()

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.

ClassB

ClassB

ClassB

ClassB

SelectedObjects

List<T>

public List<object> SelectedObjects get;

SelectedObjects.RemoveAll(item => !(item is ClassB));

2 Answers
2

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:

ClassB

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


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

List<T>

SelectedObjects get;

SelectedObjects =

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>:

object

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));


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