Reusing strings read from I/O

I am working on an application that reads lots of data from the network and puts it in a grid. I noticed that I could save some memory by reusing existing strings instead of always using the new strings that came off the wire. So here is the class that I wrote to accomplish that. It is simple and it works. But I was wondering if this had a name and, of course, if the code could be improved. One thing that I don't like is that I'm storing two references to each string.

public class StringCollection
{
  private Dictionary lookup_ = new Dictionary();

  public string Reuse(string s)
  {
    if (s == null)
    {
      return null;
    }
    string existing;
    if (lookup_.TryGetValue(s, out existing))
    {
      return existing;
    }
    else
    {
      lookup_.Add(s, s);
      return s;
    }
  }

  public void Clear()
  {
    lookup_.Clear();
  }

  public int Count { get { return lookup_.Count; } }

}

You might want to look into string interning:


The common language runtime conserves string storage by maintaining a table, called the intern pool, that contains a single reference to each unique literal string declared or created programmatically in your program. Consequently, an instance of a literal string with a particular value only exists once in the system.

While it has some memory-related side-effects, you could avoid having to build up a dictionary like this and throw away allocated strings to keep it updated.

StackExchange Code Review Q#5460, answer score: 10