等待unitl ListView的smoothScrollToPosition()完​​成

Question

范围

我需要顺利滚动到某个位置,然后"跳"到另一个位置setSelection(anotherPosition).这样做是为了创造一个平滑滚动(例如)100个项目的幻觉ListView.smoothScrollToPosition(100)你知道,持续太久了.

问题

setSelection()不等到smoothScrollToPosition完成它的工作,因此setSelection()被立即调用,用户只能看到快速跳跃;

码

private final int scrollableItems = 20;

int firstVisiblePosition = mListView.getFirstVisiblePosition();
if (firstVisiblePosition < scrollableItems) {
    mListView.smoothScrollToPosition(0);
} else {
    mListView.smoothScrollToPosition(firstVisiblePosition - scrollableItems);
    mListView.setSelection(0);
}
mListView.clearFocus();

理念

好的,我们可以改变平滑幻觉的逻辑:首先setSelection(),然后顺利滚动(我们滚动到列表顶部的第一个项目):

    int firstVisiblePosition = mListView.getFirstVisiblePosition();

    if (firstVisiblePosition < scrollableItems) {
        mListView.smoothScrollToPosition(0);
    } else {
        mListView.setSelection(scrollableItems);
        mListView.smoothScrollToPosition(0);
    }
    mListView.clearFocus();

Answer 1

final ListView listView = ...;
View listItemView = ...;
listView.smoothScrollBy(listItemView.getHeight() * NUMBER_OF_VIEWS, 
    DURATION * 2);
listView.postDelayed(new Runnable() {
    public void run() {
        listView.smoothScrollBy(0, 0); // Stops the listview from overshooting.
        listView.setSelection(0);
    }
}, DURATION);

当然,需要针对您的用例调整滚动等方向(转到列表顶部)

编辑:如果滚动的速度太高,旧解决方案可能会超调,smoothScrollBy(0,0)将停止平滑滚动,然后立即正确设置选择.