android.widget.BaseAdapter调用DataSetObservable.notifyChanged/Invalidated

本文深入探讨了Android BaseAdapter类中notifyDataXXX方法的作用,包括notifyDataSetChanged和notifyDataSetInvalidated,阐述了它们如何通知数据集的变化,并通过Cursor的调用来更新数据状态。

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在android.widget.BaseAdapter类中定义了两个notifyDataXXX方法。

public void notifyDataSetChanged() {
    mDataSetObservable.notifyChanged();
}

public void notifyDataSetInvalidated() {
    mDataSetObservable.notifyInvalidated();
}

void android.database.DataSetObservable.notifyChanged()

Invokes onChanged on each observer. Called when the data set being observed has changed, and which when read contains the new state of the data.

void android.database.DataSetObserver.onChanged()

This method is called when the entire data set has changed, most likely through a call to Cursor.requery() on a Cursor.

void android.database.DataSetObservable.notifyInvalidated()

Invokes onInvalidated on each observer. Called when the data set being monitored has changed such that it is no longer valid.

void android.database.DataSetObserver.onInvalidated()

This method is called when the entire data becomes invalid, most likely through a call to Cursor.deactivate() or Cursor.close() on a Cursor.

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