public void Dispose()

{
  //Must be called within QueuedTask.Run().
  bool TableExists(Geodatabase geodatabase, string tableName)
  {
    try
    {
      using TableDefinition tableDefinition =
        geodatabase.GetDefinition<TableDefinition>(tableName);
      return true;
    }
    catch
    {
      // GetDefinition throws an exception if the definition doesn't exist
      return false;
    }
  }
}

{
  //Must be called within QueuedTask.Run().
  bool FeatureClassExists(Geodatabase geodatabase, string featureClassName)
  {
    try
    {
      using FeatureClassDefinition featureClassDefinition =
        geodatabase.GetDefinition<FeatureClassDefinition>(featureClassName);
      return true;
    }
    catch
    {
      // GetDefinition throws an exception if the definition doesn't exist
      return false;
    }
  }
}