如何应用泛型方法

Question

I'm using FileHelper.dll for converting list into csv files and it is working perfectly.

Totally I'm having 9 Lists and corresponding 9 methods to handle file conversion and it will grow in future

Here,I have showed only 3 methods.

//-----Transaction.csv
public DateTime ExportResultsToCsv(string filePath, string HeaderLine, List<RetailTransaction> retailTxnList)
   {
      engine = new FileHelperEngine(typeof(RetailTransaction)) { HeaderText = HeaderLine };
      engine.WriteFile(filePath, retailTxnList);
            return DateTime.Now;
   }

//-----ConcessionSale.csv
public DateTime ExportResultsToCsv(string filePath, string HeaderLine, List<ConcessionSale> concessionSaleList)
    {
      engine = new FileHelperEngine(typeof(ConcessionSale)) { HeaderText = HeaderLine };
      engine.WriteFile(filePath, concessionSaleList);
      return DateTime.Now;
    }

//-----MerchandiseSale.csv
public DateTime ExportResultsToCsv(string filePath, string HeaderLine, List<MerchandiseSale> merchandiseSaleList)
  {
     engine = new FileHelperEngine(typeof(MerchandiseSale)) { HeaderText = HeaderLine };
     engine.WriteFile(filePath, merchandiseSaleList);
     return DateTime.Now;
  }

While Googling, I read some concepts in Generics however I'm not able to get an idea. My concern, it is possible to use Generics here. Like having one generic method instead of many method like above.

Please shed some light on this issue. Is it possible to reduce the number of methods?

Thanks in advance.

Answer 1

public DateTime ExportResultsToCsv<T>(string filePath, string HeaderLine, List<T> data)   
{
    engine = new FileHelperEngine(typeof(T)) { HeaderText = HeaderLine };
    engine.WriteFile(filePath, data);
    return DateTime.Now;   
}

For more info on generics see this article on MSDN

Answer 2

This is a situation where you can use generics. You would use a type variable, usually T is used so that is why you commonly see it. This variable will replace the type of your list. As a result, you will need to pass the list type when calling the method

public DateTime ExportResultsToCsv<T>(string filePath, string HeaderLine, List<T> SaleList)
{
 engine = new FileHelperEngine(typeof(T)) { HeaderText = HeaderLine };
 engine.WriteFile(filePath, SaleList);
 return DateTime.Now;
}

and then you could simply call it like this:

ExportResultsToCsv(filePath,Header,salesList)