How to handle better data from HashMap in Java? -

in order develop text editor in java, user able open several files object jtabbedpane. then, stores such files on hashmap<string,tabmanager>. (the key of hashmap), should name of file. after, have on memory files opened within of hashmap. now, need manage tabs. example, if user on tab selected it, evident user change font of text, save file selected, copy it, , on. manage tab selected user, need of class objects tab selected, just. such as, jtextpane , file. basically, should do:

    for(map.entry<string, tabmanager> entry: hashmap.entry)     {          string key = entry.getkey();          tabmanager = entry.getvalue();          if(tab.gettabselected().equals(key))         {                             // resquest objects tab selected user              this.container = tabmanager.getjtextpane();              this.file = tabmanager.getfile();         }      } 

i have on hands objects tab selected user. now, going handle it. issue is:

• how handle big amount of datas ?
• all time, have loop know tab user selected ?

how handle data ?

i can't see name of map... assuming have like:

map<string, tabmanager> map = new hashmap<>(); 

where string name of tab, unique per tab, , can name tab.gettabselected(), can do:

tabmanager selectedtab = map.get(tab.gettabselected()); 

to selected tab.

about second question: how handle big data... since don't want read , copy in memory entire file every time, want:

• start , end file pointers know chunk of file displaying
• cache tabs page each of them displays
• open file when tab selected , cache out-of-date or not covering info need, close when tab not selected anymore (and/or after time). other optimizations possible...