Android Adapter.RegisterDataSetObserver

Question

RegisterDataSetObserver 的用途是什么？我几乎到处都在寻找它(包括 documentation )，但我找不到正确的答案。

adapter.registerDataSetObserver(new DataSetObserver() {
        @Override
        public void onChanged() {
            super.onChanged();
            list1.setSelection(adp.getCount()-1);
        }
    });

这段代码的目的是什么？

Answer 1

遵循Android Official Documentation :

abstract void   registerDataSetObserver(DataSetObserver observer)

Register an observer that is called when changes happen to the data used by this adapter.

Parameters

observer -> the object that gets notified when the data set changes.

DataSetObserver类:

Receives call backs when a data set has been changed, or made invalid. The typically data sets that are observed are Cursors or Adapters.

DataSetObserver must be implemented by objects which are added to a DataSetObservable.