Detect end of ScrollView

Did it!

Aside of the fix Alexandre kindly provide me, I had to create an Interface:

public interface ScrollViewListener {
    void onScrollChanged(ScrollViewExt scrollView, 
                         int x, int y, int oldx, int oldy);
}

Then, i had to override the OnScrollChanged method from ScrollView in my ScrollViewExt:

public class ScrollViewExt extends ScrollView {
    private ScrollViewListener scrollViewListener = null;
    public ScrollViewExt(Context context) {
        super(context);
    }

    public ScrollViewExt(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public ScrollViewExt(Context context, AttributeSet attrs) {
        super(context, attrs);
    }

    public void setScrollViewListener(ScrollViewListener scrollViewListener) {
        this.scrollViewListener = scrollViewListener;
    }

    @Override
    protected void onScrollChanged(int l, int t, int oldl, int oldt) {
        super.onScrollChanged(l, t, oldl, oldt);
        if (scrollViewListener != null) {
            scrollViewListener.onScrollChanged(this, l, t, oldl, oldt);
        }
    }
}

Now, as Alexandre said, put the package name in the XML tag (my fault), make my Activity class implement the interface created before, and then, put it all together:

scroll = (ScrollViewExt) findViewById(R.id.scrollView1);
scroll.setScrollViewListener(this);

And in the method OnScrollChanged, from the interface...

@Override
public void onScrollChanged(ScrollViewExt scrollView, int x, int y, int oldx, int oldy) {
    // We take the last son in the scrollview
    View view = (View) scrollView.getChildAt(scrollView.getChildCount() - 1);
    int diff = (view.getBottom() - (scrollView.getHeight() + scrollView.getScrollY()));

    // if diff is zero, then the bottom has been reached
    if (diff == 0) {
        // do stuff
    }
}

And it worked!

Thank you very much for your help, Alexandre!

I found a simple way to detect this :

   scrollView.getViewTreeObserver()
       .addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {
            @Override
            public void onScrollChanged() {
                if (scrollView.getChildAt(0).getBottom()
                     <= (scrollView.getHeight() + scrollView.getScrollY())) {
                    //scroll view is at bottom
                } else {
                    //scroll view is not at bottom
                }
            }
        });

• Doesn't need to custom ScrollView.
• Scrollview can host only one direct child, so scrollView.getChildAt(0) is okay.
• This solution is right even the height of direct child of scroll view is match_parent or wrap_content.

All of these answers are so complicated, but there is a simple built-in method that accomplishes this: canScrollVertically(int)

For example:

@Override
public void onScrollChanged() {
    if (!scrollView.canScrollVertically(1)) {
        // bottom of scroll view
    }
    if (!scrollView.canScrollVertically(-1)) {
        // top of scroll view
    }
}

This also works with RecyclerView, ListView, and actually any other view since the method is implemented on View.

If you have a horizontal ScrollView, the same can be achieved with canScrollHorizontally(int)