How to update Sample Data in C#

I have this sample data. Right now it is defined in a seperate C# file like this:

public class SampleData{

    public static ObservableCollection<Product> GetSampleData(){
        ObservableCollection<Product> teams = new ObservableCollection<Product>();
    }

}

and I load the obsevableCollection inside GetSampleData().

It works and I am able to get the Sample-Data anywhere in my pro开发者_运维百科gram.

But how can I redesign this code so that I can create the sample data on the fly from outside the class?

What you are trying to implement is called a singleton pattern. It allows you to store a single instance of an object.

Basically your problem is that every time you call GetSampleData you are creating a new instance of the ObservableCollection<Product> so you can’t get the same data gain by calling the method again. Your actual sample I think is not what you meant because in it’s posted form it wouldn’t compile because you missed the return teams;.

I am guessing you want something like this:

public class SampleData
{ 
  private static ObservableCollection<Product> _Instance;

  public static ObservableCollection<Product> Instance
  {
    get
    {
       // Create a new collection if required.
       if (SampleData._Instance == null)
       {
          // Cache instance in static field.
          SampleData._Instance =  new ObservableCollection<Product>();
       }

       // Return new or existing collection.
       return SampleData._Instance;
    }
  }
}

Basically we are creating the object instance on the first call so when you call the Instance property again you get the same instance.

Use it like this:

// Add the data to the ObservableCollection<Product>.
SampleData.Instance.Add(new dataObjectOrWhatEver());

// Get index 0 from the collection.
var someObject = SampleData.Instance[0];

public class SampleData{

    static ObservableCollection<Product> teams = null;
    static public ObservableCollection<Product> Teams{
        get{
            if(teams == null)
                teams = GetSampleData();
            return teams;
        }
        set{
            teams = value;
        }
    }

    // make this one private
    private static ObservableCollection<Product> GetSampleData(){
        ObservableCollection<Product> t = new ObservableCollection<Product>();
        // fill t with your data
        return t;
    }
}

AND for the cunsumer:

public class MyCunsumerClass{

    // the method that uses the Team that provided by SampleData
    public void MyMethod(){
        this.flatteningTreeView.ItemsSource = SampleData.Teams;
    }

    public void MyFillerMethod(){
        var my_new_data = new ObservableCollection<Product>(); // or anything else you want to fill the Team with it.
        SampleData.Teams = my_new_data;
        // SampleData.Teams has new value you suplied!
    }

    public void MyChangerMethod(){
        var t = SampleData.Team;
        t.AnyProperty = my_value;
        t.OtherProperty = my_value_2;
        // SampleData.Team's properties changed!
    }

}