Code Repetition Confusion

Question

In my Android Application, I have two activities.

• One Activity lets the user take a picture. This picture is saved, and then uploaded to the server. The server returns some info and displays it in a list.

• The other Activity is a gallery. The user can select a picture, upload it and get the same info in a list (the same as the first activity)

The way I've implemented is this:

• upload and Info task is a seperate AsyncTask called WebServiceTask. Both Activities execute this task.

• I created a WebServiceTaskInvoker interface so that each activity could specify what happens on preExecute, postExecute, progressUpdate.

The problem is that the two activities pretty much do the exact same thing on preExecute, postExecute and progressUpdate so there's code repetition between the two activities.

• OnPreExecute: Both Activities check internet connectivity

• OnProgressUpdate: Both Activities change a TextView's text

• OnPostExecute: Both Activities create a dynamic ListView and populate it with results.

How can I fix this?

• I know one way would be to combine the two activities into one but form past experience, I've known this to be troublesome and messy.

• I could put the UI code in the WebServiceTask but that would lead to tight cohesion.

Answer 1

An alternate to Catherine's suggestion is to create an activity mode enumeration.

Pass this mode as an extra when launching your activity.

If the mode is MODE_GALLERY then load the gallery.xml layout and populate it, if not then load the other layout.

Just make sure that you use the same id's for the common views, an easy way to do this is to use the include tag in your layout files.

The advantage of this is that you only have one activity file instead of three which would be required for the subclassing method.

You may also be able use fragments, but I don't have any experience with these so I can't advise ou further.

One last note, I would avoid putting UI code into a task.

Answer 2

Implement a base class for the two activities that executes common code. Implement the activities as subclasses of your base class to execute different code.