How does Android manage memory when views are displayed?

Question

I would like to know how Android manages memory when loading views into a layout and when they are shown and then not shown on the screen.

Basically I'm making an app that requires a very very long page filled with bitmaps and text - similar to a webpage. I know I should use standard views such as GridView and ListView to handle lots of views and images but this is a niche application. (Design is set in stone)

Say I have this layout

<ScrollView>
    <LinearLayout>
        1000 ImageViews vertically stacked inside here.
    </LinearLayout>
</ScrollView>

When the ScrollView is loaded not all the ImageViews will fit on the screen - are the ImageView bitmaps that are not on the screen still loaded into memory? If not, when they are scrolled into view then scrolled out of view with they be removed from memory?

NB: I know that GridViews / ListViews are designed for this purpose but my app has a special design that can't accommodate these views.

Potential Solution: extend the gridview so that it has a fixed height and does not scroll until the ScrollView it is contained in has reached the bottom. Ie:

<ScrollView>
    <LinearLayout>
        Lots of text and a few images.
        <GridView> <-- attach listener so that touch events are 
        ignored until at bottom of scroll view -->
            1000s of ImageViews
        </GridView>
    </LinearLayout>
</ScrollView>

score 0 · Answer 1 · edited May 23 '17 at 11:49

0

Yes they are loaded into memory even if they are not visible. Doing it without using a ListView and lazy loading of images might cause your app to run out of memory on low memory devices and crash.

Also, your potential is not gonna be workable since putting things that scroll inside other things that scroll is always a bad idea and will lead to a lot of hassle related to getting the proper touch events and handling them accurately. See this answer.

edited May 23 '17 at 11:49

Community

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answered Feb 28 '13 at 04:59

Anup Cowkur

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Yeah this is what I thought might happen. – JackMahoney Feb 28 '13 at 05:01
Thanks for the update. I have placed scrollviews inside scrollviews in the past though - it can be done http://stackoverflow.com/questions/9804230/list-view-inside-a-scroll-view (my answer) – JackMahoney Feb 28 '13 at 05:10
Thanks man - will award the point if no-one else elucidates better – JackMahoney Feb 28 '13 at 05:17

How does Android manage memory when views are displayed?

1 Answers1