吐槽ExpandableListView

   需要把ExpandableListView的适配器(继承自BaseExpandableListAdapter)同时绑定到AutoCompleteTextView&＃xff0c;实现搜索过滤功能。实现了接口Filterable&＃xff0c;以为成功在即&＃xff0c;既然编译抛错误

The generic method setAdapter(T) of type AutoCompleteTextView is not applicable for the arguments (MyExpandableListAdapter). The inferred type MyExpandableListAdapter is not a valid substitute for the bounded parameter

 MyExpandableListAdapter未实现ListAdapter,跟进BaseExpandableListAdapter最终继承的接口ExpandableListAdapter既然不是ListAdapter的子类!ExpandableListView继承自ListView google既然让它实现不同的适配器&＃xff0c;哦&＃xff01;狗屎&＃xff01;

    继续看看setAdapter有两个重载

public void setAdapter(ExpandableListAdapter adapter)public void setAdapter(ListAdapter adapter)

如果调用

public void setAdapter(ListAdapter adapter)

直接就抛异常。看另外一个函数的实现

public void setAdapter(ExpandableListAdapter adapter) {// Set member variablemAdapter &＃61; adapter;if (adapter !&＃61; null) {// Create the connectormConnector &＃61; new ExpandableListConnector(adapter);} else {mConnector &＃61; null;}// Link the ListView (superclass) to the expandable list data through the connectorsuper.setAdapter(mConnector);}

  看&＃xff0c;google既然在ExpandableListAdapter和ListAdapter直接做一个链接器来适配ListView。

  ExpandableListView的这种实现方法&＃xff0c;虽然可重用listview&＃xff0c;但函数setAdapter签名和父类ListView不统一&＃xff0c;无疑给调用者添加陷阱和增加复杂度。

  回到上面的问题&＃xff1a;如果需要MyExpandableListAdapter同时能够被AutoCompleteTextView做adapter,只好乖乖实现ListAdapter,所以要实现ListAdapter、ExpandableListAdapter两个接口。这么来编译还是不能通过。

For ExpandableListView, use setAdapter(ExpandableListAdapter) instead of " &＃43;"setAdapter(ListAdapter)

 聪明的java编译器把MyExpandableListAdapter认为是ListAdapter的子类了。怎么办&＃xff1f;很简单&＃xff01;一个小技巧让编译器更加聪明点

expandableListView.setAdapter((ExpandableListAdapter)MyExpandableListAdapter);

 至此MyExpandableListAdapter就不仅可以被ExpandableListView使用而且可以被AutoCompleteTextView使用了。

 希望此文对您有用&＃xff01;