c# - Is Clearing ObservableCollection Recommended before Adding Items to it? -

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i need filter observablecollection have items in it. approach better?

// assigning filtered result directly filteredobservablecol = filteredcollectioncopy.where(i=> i.age > 25).toobservablecollection();

or 

// clearing collection first filteredobservablecol.clear(); filteredobservablecol = filteredcollectioncopy.where(i=> i.age > 25).toobservablecollection();

you use collectionviewsources instead of observablecollection bind to. there can apply filtering.

icollectionview mycollection { get; private set; }  public void loaddata() {     var myobservable = //... load/create list     mycollection = collectionviewsource.getdefaultview(myobservable);     mycollection.filter = item => ((typeofitem)item).name = "bob"; }

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