Question

我想在列表视图中添加页脚。当列表项的数量更多时，页脚工作正常。但是当listview的项目很少时，页脚会显示在屏幕中间，就在listview的下方。它看起来很破旧。在这种情况下，我希望页脚对齐父底部。谢谢你的期待。

Answer 1

也许你的listview的高度设置为wrap_content？

据我所知，页脚添加在列表视图的底部。如果将listview的高度设置为match_parent，则应将其与底部对齐，并且还应在其中显示页脚。（如果使用相对布局，只需在.xml文件中设置listview的属性alignParentBottom =“true”）

Answer 2

这是你想要的最简单的例子。你可以自定义它：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/RelativeLayout1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical" >

   <ListView
        android:id="@+id/listView1"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_above="@+id/footer"
        android:layout_alignParentLeft="true"
        android:layout_alignParentTop="true" >

    </ListView>


    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="90dp"
        android:layout_alignParentBottom="true"
        android:layout_alignParentLeft="true"
        android:layout_alignParentRight="true"
        android:id="@+id/footer" >

    </RelativeLayout>


</RelativeLayout>

如果你想这样做，你在评论中说，你必须在代码中设置页脚的布局参数，你必须得到列表的大小，然后得到屏幕上显示的行数，然后

 if (listSize < numRow)
     //set footer to bottom of your list
 else
     //  android:layout_alignParentBottom="true"

Answer 3

您可以将RecyclerView与RecyclerView.ItemDecoration一起使用来实现此行为。

public class StickyFooterItemDecoration extends RecyclerView.ItemDecoration {

/**
 * Top offset to completely hide footer from the screen and therefore avoid noticeable blink during changing position of the footer.
 */
private static final int OFF_SCREEN_OFFSET = 5000;

@Override
public void getItemOffsets(Rect outRect, final View view, final RecyclerView parent, RecyclerView.State state) {
    int adapterItemCount = parent.getAdapter().getItemCount();
    if (isFooter(parent, view, adapterItemCount)) {
        //For the first time, each view doesn't contain any parameters related to its size,
        //hence we can't calculate the appropriate offset.
        //In this case, set a big top offset and notify adapter to update footer one more time.
        //Also, we shouldn't do it if footer became visible after scrolling.
        if (view.getHeight() == 0 && state.didStructureChange()) {
            hideFooterAndUpdate(outRect, view, parent);
        } else {
            outRect.set(0, calculateTopOffset(parent, view, adapterItemCount), 0, 0);
        }
    }
}

private void hideFooterAndUpdate(Rect outRect, final View footerView, final RecyclerView parent) {
    outRect.set(0, OFF_SCREEN_OFFSET, 0, 0);
    footerView.post(new Runnable() {
        @Override
        public void run() {
            parent.getAdapter().notifyDataSetChanged();
        }
    });
}

private int calculateTopOffset(RecyclerView parent, View footerView, int itemCount) {
    int topOffset = parent.getHeight() - visibleChildsHeightWithFooter(parent, footerView, itemCount);
    return topOffset < 0 ? 0 : topOffset;
}

private int visibleChildsHeightWithFooter(RecyclerView parent, View footerView, int itemCount) {
    int totalHeight = 0;
    //In the case of dynamic content when adding or removing are possible itemCount from the adapter is reliable,
    //but when the screen can fit fewer items than in adapter, getChildCount() from RecyclerView should be used.
    int onScreenItemCount = Math.min(parent.getChildCount(), itemCount);
    for (int i = 0; i < onScreenItemCount - 1; i++) {
        totalHeight += parent.getChildAt(i).getHeight();
    }
    return totalHeight + footerView.getHeight();
}

private boolean isFooter(RecyclerView parent, View view, int itemCount) {
    return parent.getChildAdapterPosition(view) == itemCount - 1;
}

}

确保为RecyclerView高度设置 match_parent 。

请查看示例应用https://github.com/JohnKuper/recyclerview-sticky-footer及其工作原理http://sendvid.com/nbpj0806

此解决方案的一个巨大缺点是它只能在整个应用程序（不在装饰内）中的notifyDataSetChanged（）之后正常工作。通过更具体的通知，它无法正常工作并支持它们，它需要更多逻辑。此外，您可以通过 eowise 从图书馆 recyclerview-stickyheaders 获取见解，并改进此解决方案。

如果列表中的项目非常少，如何在页面末尾显示页脚视图？

3 个答案: