Question

I can’t work out how to do a “find” on a List I have based on use of a value that I’ll pass in at run time. If you see my below code, I want to be able to find the CustomClass in the List for which it’s Path parameter is equal to X, where X will be defined at run time.

Any ideas how to do such a find on a List? Or is this not possible without writing an iterator and doing the find manually? In which case perhaps there is a key’ed collection I should look at using instead?

   private List<CustomClass> files;

   public void someMethod()
  {
       Uri u= new Uri(www.test.com);
       CustomClass cc = this.files.find( matchesUri(u) );  // WON'T LET ME DO THIS
  }

   private static bool matchesUri(List<CustomClass> cc, Uri _u)
    {
        return cc.Path == _u;           }


public class CustomClass
{
    private Uri path;

    public Uri Path
    {
        get { return this.path; }
        set { this.path = value; }
    }
}

PS. I must admit I don’t quite follow the predicate stuff in the doco at http://msdn.microsoft.com/en-us/library/x0b5b5bc.aspx

Answer 1

Use a lambda:

 Uri u = new Uri("www.test.com");
 CustomClass cc = this.files.Find(cc => cc.Path == u);

or if you still want a named method:

static bool matchesUri(CustomClass cc, Uri _u)
{
    return cc.Path == _u;
}

 Uri u = new Uri("www.test.com");
 CustomClass cc = this.files.Find(cc => matchesUri(cc, u));