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一直认为notifyDataSetChanged 是 用来刷新数据的 当数据发生变化的时候调用notifyDataSetChanged
官方说：通知任何注册的观察者数据发生了改变(Notify any registered observers that the data set has changed) –自己翻译的不保证完全正确。。。。。。
今天有空翻阅下源码
public final void notifyDataSetChanged() {
mObservable.notifyChanged();
}
在看看 notifyChanged()方法
public void notifyChanged() {
// since onChanged() is implemented by the app, it could do anything, including
// removing itself from {@link mObservers} - and that could cause problems if
// an iterator is used on the ArrayList {@link mObservers}.
// to avoid such problems, just march thru the list in the reverse order.
for (int i = mObservers.size() - 1; i >= 0; i--) {
mObservers.get(i).onChanged();
}
}
这里的mObservers 是一个list
protected final ArrayList<T> mObservers = new ArrayList<T>();
这样看来notifyDataSetChanged 是改变list 的元素
在看下源码的注释
相似的方法
* @see #notifyItemChanged(int) * @see #notifyItemInserted(int) * @see #notifyItemRemoved(int) * @see #notifyItemRangeChanged(int, int) * @see #notifyItemRangeInserted(int, int) * @see #notifyItemRangeRemoved(int, int)
/**
* Notify any registered observers that the data set has changed.
*
* <p>There are two different classes of data change events, item changes and structural
* changes. Item changes are when a single item has its data updated but no positional
* changes have occurred. Structural changes are when items are inserted, removed or moved
* within the data set.</p>
*
* <p>This event does not specify what about the data set has changed, forcing
* any observers to assume that all existing items and structure may no longer be valid.
* LayoutManagers will be forced to fully rebind and relayout all visible views.</p>
*
* <p><code>RecyclerView</code> will attempt to synthesize visible structural change events
* for adapters that report that they have {@link #hasStableIds() stable IDs} when
* this method is used. This can help for the purposes of animation and visual
* object persistence but individual item views will still need to be rebound
* and relaid out.</p>
*
* <p>If you are writing an adapter it will always be more efficient to use the more
* specific change events if you can. Rely on <code>notifyDataSetChanged()</code>
* as a last resort.</p>
可以看到官方说 notifyDataSetChanged 的作用
Notify any registered observers that the data set has changed. 通知任何注册的观察者数据发生了改变
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