CODEWITHSUNDEEP
androidandroid-layoutandroid-listviewandroid-view
Glenn.nz
Glenn.nz

Reputation: 2291

Android Layout efficiency, multiple views or single with hidden views?

I have a ListView with layouts in them. Sometimes the layouts need to look one way, sometimes the other. They are mainly text laid out in different areas with different weights sizes etc. The ratio of main views compared to other views is about 5:1. When it needs to be changed only 2/3 of the whole view changes.

I think I have two options :

  1. (the way it is now) One layout(so it never has to be re-inflated, as the recycled views are all the same) and the 2nd 2/3 of the view is hidden until it is needed to be changed, then code will reveal it and hide the original 2/3 of the view.

  2. (other way) Two layouts, with the 1/3 layout duplicated, and each having its on other 2/3. Then when one of the different layouts needs to be used, the old view from the ListView recycler gets thrown away and a new correct view is inflated, and back again when the list is moved.

So what I am asking here is that is it better to hide/show parts of the same layout to prevent the recycler in a ListView from inflating more layouts, or have two cut-down layouts with no extra hidden views, and have them inflated when they are needed?

Upvotes: 6

Views: 1277

Answers (2)

user
user

Reputation: 87064

If the TextViews are the main part of those layouts, I don't think there is going to be a big difference in performance so you could go either way. I would go with option two because:

  1. The ratio between the number of normal rows layout vs special rows is big. If you keep the single layout approach then you'll have to modify the layouts in code for each of the rows, normal or special, because you could be dealing with a recycled View that has 2/3 part hidden when it's time to show a normal one(so you end up modifying the layout each time). If you were to use the second option then you could eliminate this part from the getView method and simply use a switch to see with what row type you're dealing with(no more modification of the row layout each time in the getView method, you let the ListView handle that by providing you with the correct type of row layout). Don't worry about inflating another layout file(once), this isn't the performance hit to be afraid of.

  2. Using one type of layout it means you're having Views remaining in memory even if the user doesn't see them(so you may be preventing the ListView from inflating more Views(only one time, in fact) but at the same time you're occupying more memory with the ones you even don't show to the user). The first option has the advantage that the binding of data to the row is more simple as you have all the views at your disposal(even if the user doesn't see a part of them) instead of the second option, where you would have to see which data need to be shown based on row type.

  3. Code readability. Having two row types and testing to see which one you get in the getView method it's more meaningful as you see what logic you have for each type of row. Also, it will be better if you plan to change those row layouts in the future or add more row types.

The ListView does a great job on recycling views as long as you help it with providing the row types. Edit: The ListView will keep a recycled view for each type you declare in the adapter. So the ListView will inflate the second layout only the first time it finds it in the ListView, next time when it will need a row with with type it will use the recycled one(and it will maintain 2 types of recycled views, the first and second row type).

Upvotes: 3

user387184
user387184

Reputation: 11053

Actually this little bit of extra GC IMHO should not be the driver for your decision.

I would go the route that is easier to maintain and understand.

Also there is an nice useful include tag in xml like this:

<include
    android:id="@+id/abc"  
    android:layout_height="wrap_content"
    android:layout_width="fill_parent"
    layout="@layout/abc"   , where abc = the xml  file you want to include
    />

Upvotes: 0

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