Question

我有一个listview，可以根据请求添加其他视图，这些视图由BaseAdapter维护。如何在更新后保持滚动位置？

我知道这已被问过几次，但每次都提出了相同的解决方案，我已经尝试过，这是在更新包含列表内容的ArrayList之后调用adapter.notifyDataSetChanged();。 / p>

如何确保保持滚动位置？

Answer 1

在您的活动类中实施OnScrollListener，然后使用以下代码：

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更新数据，则可以在PostExecute()中加入以下内容以保持滚动位置：

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

我希望这会有所帮助。

Answer 2

我采取的方法是在更新后调用ListView.setSelection(position)滚动到所需的position。

根据您拨打电话的位置，您可能需要在致电requestFocusFromTouch之前致电setSelection，以确保项目的位置正确。

Answer 3

此代码可以帮助您....

// get position of listview
int index = listView.getFirstVisiblePosition();
View v = listView.getChildAt(0);
int top = (v == null) ? 0 : v.getTop();

// notify dataset changed or re-assign adapter here

//re-assign the position of listview after setting the adapter again
listView.setSelectionFromTop(index, top);

干杯：）

Answer 4

你可以试试这个：

//Get the top position from the first visible element
int fVisible = list.getFirstVisiblePosition();
View vFirst = list.getChildAt(0);
int pos = 0;
if (vFirst != null) pos = vFirst.getTop();

//Restore the position
list.setSelectionFromTop(fVisible, pos);

Answer 5

您可以执行以下操作。如果你想通过滚动到底部加载更多数据，它会有一些变化。

int currentFirstVisibleItem, currentScrollState;
int countChange = 0;
public void onScroll(AbsListView view, int firstVisibleItem, int visibleItemCount, int totalItemCount) {
    Log.d("Scroll", "Scrolling");
    this.currentFirstVisibleItem = firstVisibleItem;
    countChange = 0;//during touching you can decide not to refresh by scroll
}

public void onScrollStateChanged(AbsListView view, int scrollState) {
    Log.d("Scroll", "Changed");
    this.currentScrollState = scrollState;
    if (scrollState == SCROLL_STATE_TOUCH_SCROLL) {
        countChange = 0;
    }
    if (++countChange > 1) {
        //scroll to top and release touch change=2. Simple scroll and release touch change=1
        this.isScrollCompleted();
        countChange = 0;
    }
}

private void isScrollCompleted() {
    Log.d("Load", "Reload");
    if (currentFirstVisibleItem == 0) {
        //Your loading go here
    }
}

Android ListView - 在更新时滚动回到顶部

5 个答案: