how to clear singleton class field

Question

friend's

   I have list of menus below the title bar and it have menus like
        All Article   | Top10  | 

when i select All Article menu it parse and list the data and below the last list row i have button to load more data in list,for that purpose i used singleton class when i click the Top10 menu i have to do the same but here i need to clear the singleton class fields,i tried to set singleton class instance to be null in clear() ,but it doesn't clear the field values again it shows the All Article list data.,i never used individual activity for each menu,all i'm doing in same activity.plz help me.

Thanks in advance.