Android ListView - 更新时滚动回顶部 [英] Android ListView - scrolls back to top on update

问题描述

我有一个列表视图，可以根据请求添加其他视图，由 BaseAdapter 维护.更新后如何保持滚动位置?

I have a listview that gets additional views added on request, that's maintained by a BaseAdapter. How can I maintain scroll position after the update?

我知道这已经被问过几次了，但每次都提出了同样的解决方案，我试过了，就是在更新后调用adapter.notifyDataSetChanged();包含列表内容的 ArrayList.

I know this has been asked a few times, but each time, the same solution has been put forward, which I have tried, which is to call adapter.notifyDataSetChanged(); after updating the ArrayList that contains the list contents.

如何确保滚动位置保持不变?

How can I ensure that scroll position is maintained?

推荐答案

在您的活动类中实现一个 OnScrollListener ，然后使用以下代码:

Implement an OnScrollListener in your activity class and then use the following code:

int currentFirstVisibleItem, currentVisibleItemCount, currentTotalItemCount;
public void onScroll(AbsListView view, int firstVisibleItem,
        int visibleItemCount, int totalItemCount) {
    this.currentFirstVisibleItem = firstVisibleItem;
    this.currentVisibleItemCount = visibleItemCount;
    this.currentTotalItemCount = totalItemCount;
}

public void onScrollStateChanged(AbsListView view, int scrollState) {
    this.currentScrollState = scrollState;
    this.isScrollCompleted();
}

private void isScrollCompleted() {

    if (currentFirstVisibleItem + currentVisibleItemCount >= currentTotalItemCount) {
        if (this.currentVisibleItemCount > 0
                && this.currentScrollState == SCROLL_STATE_IDLE) {

            //Do your work
        }
    }
}

如果您使用 AsyncTask 来更新您的数据，那么您可以在 PostExecute() 中包含以下内容以保持滚动位置:

If you are using AsyncTask for updating your data, then you can include the following in your PostExecute() in order to maintain the Scroll position:

list.setAdapter(adapter);
list.setSelectionFromTop(currentFirstVisibleItem, 0);

我希望这会有所帮助.

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