check if an android scrollview can scroll

问题

Do you know if it is possible to know if an Android Widget ScrollView can scroll? If it has enough space it doesn't need to scroll, but as soon as a dimension exceeds a maximum value the widget can scroll.

I don't see in the reference a method who can give this information. Maybe is it possible to do something with the size of the linearlayout inside the scrollview?

回答1:

I used the following code inspired by https://stackoverflow.com/a/18574328/3439686 and it works!

ScrollView scrollView = (ScrollView) findViewById(R.id.scrollView);
int childHeight = ((LinearLayout)findViewById(R.id.scrollContent)).getHeight();
boolean isScrollable = scrollView.getHeight() < childHeight + scrollView.getPaddingTop() + scrollView.getPaddingBottom();

回答2:

Thanks to: @johanvs and https://stackoverflow.com/a/18574328/3439686

private boolean canScroll(HorizontalScrollView horizontalScrollView) {
    View child = (View) horizontalScrollView.getChildAt(0);
    if (child != null) {
        int childWidth = (child).getWidth();
        return horizontalScrollView.getWidth() < childWidth + horizontalScrollView.getPaddingLeft() + horizontalScrollView.getPaddingRight();
    }
    return false;

}

private boolean canScroll(ScrollView scrollView) {
    View child = (View) scrollView.getChildAt(0);
    if (child != null) {
        int childHeight = (child).getHeight();
        return scrollView.getHeight() < childHeight + scrollView.getPaddingTop() + scrollView.getPaddingBottom();
    }
    return false;
}

回答3:

In addition to @johanvs response:

You should wait for view beign displayed

 final ScrollView scrollView = (ScrollView) v.findViewById(R.id.scrollView);
    ViewTreeObserver viewTreeObserver = scrollView.getViewTreeObserver();

    viewTreeObserver.addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
        @Override
        public void onGlobalLayout() {
            scrollView.getViewTreeObserver().removeOnGlobalLayoutListener(this);
            int childHeight = ((LinearLayout) v.findViewById(R.id.dataContent)).getHeight();
            boolean isScrollable = scrollView.getHeight() < childHeight + scrollView.getPaddingTop() + scrollView.getPaddingBottom();
            if (isScrollable) {
                //Urrah! is scrollable
            }
        }
    });

来源：https://stackoverflow.com/questions/24990992/check-if-an-android-scrollview-can-scroll