ObservableCollection Foreach

Hi,

I am using MVVM in wpf. here is my sample code as below:

Model:

        private string fruit;
        public string Fruit
        {
            get { return fruit; }
            set { fruit = value; OnPropertyChanged("Fruit"); }
        }

ViewModel:

....................................
private ObservableCollection<DemoModel> fruits = new ObservableCollection<DemoModel>();
        public ObservableCollection<DemoModel> Fruits
        {
            get { return fruits; }
            set { fruits = value; OnPropertyChanged("Fruits"); }
        }

        public void LoadFruit()
        {
            fruits.Add(new DemoModel(null, null) { Fruit = null });
            fruits.Add(new DemoModel(null, null) { Fruit = "Mango" });
            fruits.Add(new DemoModel(null, null) { Fruit = "Orange" });
        }

        private void ButtonClick(object obj)
        {
            foreach (var item in Fruits)
            {
                MessageBox.Show(item.ToString());  ???????
            }
        }

How to get the data foreach observablecollection when i clicked button event?