http://zhidao.baidu.com/link?url=mgs08yinrG-rt2864QvlbKmdbyn9rm-KTqm1CODNQpVLnVvAndkJRVJ8mN4_XkNDB2_wjojcNKO_xgMuTQe2912g9T4OQ7TlCcrRAm0sF7W

T extends Adapter 表示T是Adapter 的派生类 AdapterView
    
     表示AdapterView是模板类，T是模板参数类型
    

/**  * Returns the adapter currently associated with this widget.  *  * @return The adapter used to provide this view's content.  */ public abstract T getAdapter();