Android RecyclerView notifyItemRangeChanged vs notifyItemChanged

Question

我有一个数据集，刷新后可能会发生变化。确定现有数据集中的哪些条目已更改是非常不可预测的。我通读了 recyclerview 适配器说明，我的主要问题是。

确定哪个数据视图已更改，然后对受影响的范围使用 notifyItemRangeChanged 是否更有效，还是应该在更改每个数据视图后一一更改它们然后 notifyItemChanged？

它变得稍微复杂一些，因为根据更改的内容，每个视图的顺序可能已经更改，然后是调用 notifyItemRangeInserted、notifyItemRangeRemoved 为受影响的范围或 notifyItemMoved 的参数？

用一种方法或另一种方法更有效吗？

谢谢

Answer 1

这里是源代码，v7-22.1.1

    /**
     * Notify any registered observers that the item at <code>position</code> has changed.
     *
     * <p>This is an item change event, not a structural change event. It indicates that any
     * reflection of the data at <code>position</code> is out of date and should be updated.
     * The item at <code>position</code> retains the same identity.</p>
     *
     * @param position Position of the item that has changed
     *
     * @see #notifyItemRangeChanged(int, int)
     */
    public final void notifyItemChanged(int position) {
        mObservable.notifyItemRangeChanged(position, 1);
    }

    /**
     * Notify any registered observers that the <code>itemCount</code> items starting at
     * position <code>positionStart</code> have changed.
     *
     * <p>This is an item change event, not a structural change event. It indicates that
     * any reflection of the data in the given position range is out of date and should
     * be updated. The items in the given range retain the same identity.</p>
     *
     * @param positionStart Position of the first item that has changed
     * @param itemCount Number of items that have changed
     *
     * @see #notifyItemChanged(int)
     */
    public final void notifyItemRangeChanged(int positionStart, int itemCount) {
        mObservable.notifyItemRangeChanged(positionStart, itemCount);
    }

所以，notifyItemChanged(int) 是 notifyItemRangeChanged(int, int)

Answer 2

如果可能的话，RecyclerView '还没有'做任何努力来合并这些更改事件，尽管这是我们正在考虑的事情（低优先级）。

除非您要分派数百个事件，否则应该没问题，但如果您可以分派Range 事件，当然对 RecyclerView 更好。