将滚动视图恢复到Onresume上的某个位置

Question

i have a scroll view on my layout and many buttons after scrolling and choosing a button when it returns back to the layout the scroll view starts at the top. i wanted the scroll view to starts from where the user stops. please help am a beginner in android so please explain briefly.

Answer 1

You'll have to save your scroll view's position before your Activity or Fragment gets Destroyed.

You can save value on onSaveInstanceState

//save value on onSaveInstanceState
protected void onSaveInstanceState(Bundle outState) {
    super.onSaveInstanceState(outState);
    outState.putIntArray("SCROLL_POSITION",
            new int[]{ mScrollView.getScrollX(), mScrollView.getScrollY()});
}

and then restore it on onRestoreInstanceState

//Restore them on onRestoreInstanceState
protected void onRestoreInstanceState(Bundle savedInstanceState) {
    super.onRestoreInstanceState(savedInstanceState);
    final int[] position = savedInstanceState.getIntArray("SCROLL_POSITION");
    if(position != null)
        mScrollView.post(new Runnable() {
            public void run() {
                mScrollView.scrollTo(position[0], position[1]);
            }
        });
}

The above is just an example for more details see THIS BLOG and This post on SO .

Answer 2

The best solution is described here: Link
In few words: You have to support orientation changing, so saving the X and Y position of the scroll bar is no the best solution. Instead you have to get the position of the top visible item and scroll to it.