Android的 - 什么是adapter.notifyDataSetInvalidated办? [英] Android - What does adapter.notifyDataSetInvalidated do?
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问题描述
什么是方法adapter.notifyDataSetInvalidated()完成? 目前它没有文档。
What does the method adapter.notifyDataSetInvalidated() accomplish? There is no documentation on it.
我想重新加载ListView和notifyDataSetChanged或notifyDataSetInvalidated似乎并没有完成任何事情。
I am trying to reload a ListView and notifyDataSetChanged or notifyDataSetInvalidated don't seem to accomplish anything.
推荐答案
这取决于适配器实现......如果你把源$ C $一脸c您将看到:
It depends on the adapter implementation... if you take a look of the source code you will see that:
-
notifyDataSetInvalidated()
调用notifyInvalidated()
的DataSetObservable
类(<一href="http://www.google.com/$c$csearch/p?hl=es#uX1GffpyOZk/core/java/android/widget/BaseAdapter.java&q=android%20notifyDataSetInvalidated&sa=N&cd=1&ct=rc">see这里) - 之后,
notifyInvalidated()
调用onInvalidated()
方法为每个DataSetObserver
(<一href="http://www.google.com/$c$csearch/p?hl=es#uX1GffpyOZk/core/java/android/database/DataSetObservable.java&q=android%20DataSetObservable&sa=N&cd=1&ct=rc">see这里)。 - 接下来是有趣的部分:
onInvalidated()
<一个href="http://www.google.com/$c$csearch/p?hl=es#uX1GffpyOZk/core/java/android/database/DataSetObserver.java&q=android%20DataSetObserver&sa=N&cd=1&ct=rc">does没有做任何事情 ...
notifyDataSetInvalidated()
calls thenotifyInvalidated()
of theDataSetObservable
class (see here)- Then,
notifyInvalidated()
calls theonInvalidated()
method for eachDataSetObserver
(see here). - Then comes the funny part:
onInvalidated()
does not do anything...
这是它的实现:
public void onInvalidated() {
// Do nothing
}
DataSetObserver
是一个抽象类,所以它的子类来决定该怎么办了 onInvalidated()
DataSetObserver
is an abstract class, so it's up to the subclass to decide what to do on onInvalidated()
.
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