Question

As we all know, PictureListener is an interface with a single public method: onNewPicture(WebView view, Picture picture).

It works for simple scenarios but in my case I need to handle various errors (due to the predictably unpredictable nature of the Internet, especially via WiFi/3G).

For that, I intend to create a slightly more complex class, implementing PictureListener and having some extra state information and associated handler functions. So far so good, but…

One of the function needs access to the WebView – the same WebView that is passed as a parameter in onNewPicture() but isn’t available to PictureListener anywhere else.

So, I was thinking of passing that WebView as a parameter to the constructor of MyPictureListener and saving it as a private data member.

I haven’t seen an example of such implementation before and I am not sure whether I would be violating a rule with which I am not familiar.

Does a PictureListener that has a WebView data member make sense? Are there pitfalls that I should be aware of?

Answer 1

No, it doesn’t.

You won’t be violating rules but you will be going against the “mindset” of the WebView & PictureListener design:

1. PictureListener is an interface and
   doesn’t receive WebView as a
   parameter.
2. WebView, on the other hand, has a
   dedicated method for associating a
   PictureListener with it. So WebView
   “knows” about PictureListener.

Instead of passing a WebView parameter to PictureListener’s constructor, just cast the view parameter in onNewPicture() to your WebView and call a method in your WebView that access anything in it.