List.RemoveAll和List.FindAll结合产生的性能问题之后...

原代码：

当时entityList中的数据量：4704；length : 2

private static void OperateRemove ( List<Entity> entityList, int length) {

entityList.RemoveAll( delegate( Entity entity) {
List<Entity > list = entityList.FindAll( delegate( Entity innerEntity) {
return entity.A== innerEntity.A

} );
return null != list && list .Count < length;
} );

}

第一方案：初步认为是数据未排序，所以FindAll会慢。所以

private static void OperateRemove ( List<Entity> entityList, int length) {

entityList.Sort( delegate( Entity entity1, HotelRoomPriceEntity entity2) {
return entity1.A.CompareTo( entity2.A);
} );

entityList.RemoveAll( delegate( Entity entity) {
List<Entity > list = entityList.FindAll( delegate( Entity innerEntity) {
return entity.A== innerEntity.A

} );
return null != list && list .Count < length;
} );

}

当时程序跑过之后，微秒时间为：7901

第二方案：看来问题瓶颈还是在FindAll，所以通过一次查询先把要删除的entity.A查找出来，后面集中删除。

private static void OperateRemove ( List<Entity> entityList, int length) {

entityList.Sort( delegate( Entity entity1 , Entity entity2 ) {
return entity1.A.CompareTo( entity2.A);
} );
int eachACount = 0;
int A= 0;
int nextA= 0;
List<int> lackAEntityList= new List<int>();
foreach ( Entity entity in entityList) {
if ( 0 == A) {
A= entity.A;
nextA= entity.A;
}
else {
nextA= entity.A;
}
if ( A != nextA) {
if ( length> eachACount ) {
lackAEntityList.Add( roomId );
}
A = nextA;
eachACount = 0;
}
eachACount ++;
}
entityList.RemoveAll( delegate( Entity entity) {
return lackAEntityList.Exists( delegate( int A) {
return entity.A== A;
} );
} );

}

当时程序跑过之后，微秒时间为：40

当然还有其他解决方案:如使用sortlist＋binarySearch,Etc.

不过40对我们来说，已经比较理想。

另外附上

目标：
/// 根据A-List中的HotelID查找B-List中RoomID为0,
/// 删除对应B-List中的有关于HotelID所有RoomId全为空的配备信息
/// 同时也要删除A-List中对应的信息

public List<RoomEntity> RemoveRoomIDAllEmpty()
{
///创建存放RoomID不为空的HotelIDList
List<Int32> hotelIdList = new List<int>();

roomList.ForEach(delegate(RoomEntity re)
{
if (hotelList.Contains(re.HotelId))
{
if (re.roomId != 0)
{
hotelIdList.Add(re.HotelId);
}
}
});

//删除RoomList中的有关于HotelID所有RoomId全为空的配备信息
roomList.RemoveAll(delegate(RoomEntity re)
{
return !hotelIdList.Contains(re.HotelId);
});

//删除HotelList中的对应信息
hotelList.RemoveAll(delegate(Int32 i)
{
return !hotelIdList.Contains(i);
});

return roomList;
}

List<Int32> hotelList = new List<Int32> {
1,2,3,4,5,6,7,8,9,10
};

List<RoomEntity> roomList = new List<RoomEntity> {
new RoomEntity{ HotelId =1,roomId=1111},
new RoomEntity{ HotelId =1,roomId=0},
new RoomEntity{ HotelId =1,roomId=1111},
new RoomEntity{ HotelId =1,roomId=0},
new RoomEntity{ HotelId =1,roomId=1111},
new RoomEntity{ HotelId =2,roomId=0},
new RoomEntity{ HotelId =2,roomId=0},
new RoomEntity{ HotelId =2,roomId=0},
new RoomEntity{ HotelId =2,roomId=0},
new RoomEntity{ HotelId =4,roomId=1111},
new RoomEntity{ HotelId =5,roomId=1111},
new RoomEntity{ HotelId =3,roomId=1111},
new RoomEntity{ HotelId =4,roomId=1111},
new RoomEntity{ HotelId =1,roomId=1111},
new RoomEntity{ HotelId =6,roomId=1111},
new RoomEntity{ HotelId =1,roomId=1111},
new RoomEntity{ HotelId =5,roomId=1111},
new RoomEntity{ HotelId =8,roomId=1111},
new RoomEntity{ HotelId =7,roomId=0},
new RoomEntity{ HotelId =4,roomId=1111},
new RoomEntity{ HotelId =8,roomId=1111},
new RoomEntity{ HotelId =9,roomId=1111},
new RoomEntity{ HotelId =10,roomId=0},
new RoomEntity{ HotelId =10,roomId=0}
};