Question

I’m using JQuery to call a Java Servlet from multiple places to call multiple different methods within the servlet. At the moment, I pass a string (called methodName) and then using an ever increasing IF ELSE block to see which function to call:

public String methodCaller(String methodName) throws SQLException, IOException
{
    if(methodName.equals("method1"))
    {
        return method1(attr("permit"));
    }
    else if(methodName.equals("method2"))
    {
        return method2(attr("ring"));
    }
    else if(methodName.equals("method3"))
    {
        return method3(attr("gridRef"));
    }
    else if(methodName.equals("method4"))
    {
        return method4(attr("ring"));
    }
    else if(methodName.equals("method6"))
    {
        return method6(attr("ring"), Integer.parseInt(attr("quantity")));
    }

However, this seems awfully clunky and inefficient to me, especially as the amount of methods will increase in future. Is there a more efficient way to compare the strings? Or should I simply make a separate servlet for each method (and simply do the processing in the processRequest?

Answer 1

I would recommend making each one of your methods an object that implements a simple interface. In your class, create a HashMap linking each implementation of the interface to its respective key.

Interface

public interface MyMethod {
   public String call();
}

Implementation

   public class MethodOne implements MyMethod{

   }

Mapping & Call

    private Map<String, MyMethod> mappings = new HashMap<String,MyMethod>();

    static{
        mappings.put("method1", new MethodOne());
        //.. other mappings
    }

   public String methodCaller(String methodName) throws SQLException, IOException
   {
      MyMethod myMethod = mappings.get(methodName);
      return myMethod.call();
   }