Defining common handler for click elements in GWTQuery

Question

In my GWTQuery project, I have a situation where there are 4 custom drop-down menus. Whenever a user changes any of the current menu choice, an AJAX request is made with the values of the 4 menus (one of which is the newly changed value of that menu). Since all the 4 menus trigger similar request, I though that I will write a common class to handle the AJAX request, then let the clickhandlers extend that class.

But then, the menus being dynamically generated, I have to resort to GWTQuery's live method. And that takes a variable of type Function as parameter. Since it already extends Function, I can't make it extend my Ajax handler class as well. So how do I do it? Something like this is what I am looking for:

class f extends Funnction, AJAX_Handler {
 public boolean f(Event e) {
  ...
  return true;
  }
 public void request(int i1,int i2,int i3,int i4) {
  //for handling the request, defined in the AJAX_Handler class
  ...
  }
 }

One thing, defining a generic handler for all 4 menus which contains the AJAX_handler functions, then detecting which menu is the current handler referring to is a no-no. The AJAX_handler class has to be a separate one.

Sednus · Accepted Answer · 2013-01-22T20:03:17.440

1

Define interfaces instead.

 public interface AJAX_Handler
 {
    public void request(int i1,int i2,int i3,int i4);

 }

Then in your actual class implement the defined interface.

 class f extends Funnction implements AJAX_Handler
 {
   public boolean f(Event e) {
      ...
    return true;
    }
   public void request(int i1,int i2,int i3,int i4) {
   //for handling the request, defined in the AJAX_Handler class
    ...
    }
  }

[EDIT] Given that you need to keep the functionality in the same place. I think the simplest fix would be to define the AJAX_Handler interface then have an implemented class. For example:

 public class AJAX_HandlerImpl implements AJAX_Handler
 {
    public void request(int i1,int i2,int i3,int i4){
         //do whats necessary
     }
 }

Then use composition in your f class. Something like:

 class f extends Funnction implements AJAX_Handler
 {
   private AJAX_HandlerImpl impl = new AJAX_HandlerImpl();

   public boolean f(Event e) {
      ...
    return true;
    }

   public void request(int i1,int i2,int i3,int i4) {
          impl.request(i1,i2,i3,i4);
    }
  }

edited Jan 22 '13 at 20:03

answered Jan 22 '13 at 19:48

Sednus

2,095
1
18
35

The definition for the `request` function is pretty large and complicated. So if I declare it just as an interface, I will have to impleement it fully for all 4 handlers, exactly the thing I am trying to avoid.. – SexyBeast Jan 22 '13 at 19:52
I don't see a reason why it wouldn't. But I guess you will have to find out for sure. – Sednus Jan 22 '13 at 20:18
Yeah, that's true. Lemme check...But that's a great idea nonetheless, will definitely award a bounty tomorrow... – SexyBeast Jan 22 '13 at 20:20
Wow. Works like a charm! Thanks a ton, mate! I will award a bounty tomorrow, the least I can do for such great help! – SexyBeast Jan 22 '13 at 21:47

Defining common handler for click elements in GWTQuery

1 Answers1