Question

I’m currently developing an app that uses a ViewPager, the problem is that the way I’m doing it makes it extremely slow to start and takes up tonnes of memory.

I’m implementing the pageradapter like so:

        public MyPagerAdapter(Context context) {
        views = new ArrayList<RelativeLayout>();
        views.add(new SliderLayout(context, "slide 8"));
        views.add(new SliderLayout(context, "slide 1"));
        views.add(new SliderLayout(context, "slide 2"));
        views.add(new SliderLayout(context, "slide 3"));
        views.add(new SliderLayout(context, "slide 4"));
        views.add(new SliderLayout(context, "slide 5"));
        views.add(new SliderLayout(context, "slide 6"));
        views.add(new SliderLayout(context, "slide 7"));
        views.add(new SliderLayout(context, "slide 8"));
        views.add(new SliderLayout(context, "Slide 1"));
    }

All the layoutobjects contain a FrameLayout with a textView and a panel that contains a webview with local html. All the layouts have unique content, that is loaded and inflated when the SliderLayout class is instantiated.

I also attempted to add views on the fly in the instantiateItem method, but that just makes the scrolling more dodgy and will give an OutOfMemory fatal exception if I scroll too fast.

So my question is, what is the best way to implement a ViewPager that contains several unique views (but based on the same layout), so it doesn’t consume so much memory and starts quicker?

Answer 1

You must attach your views to pager in instantiateItem() (like you do it in regular adapter’s getView() method). In this case ViewPager takes care about memory management. Take a look into demo project in CompatibilityPackage. Actually you can have thousands of pages without any lags.

@Override
public Object instantiateItem(View collection, int position) {
    View v = layoutInflater.inflate(...);
    ...
    ((ViewPager) collection).addView(v,0);
    return tv;
}

@Override
public void destroyItem(View collection, int position, Object view) {
    ((ViewPager) collection).removeView((TextView) view);
}