android - ListView position doesn't save after close -

i managed change listview's item position after close app, position goes before made changes.

what , how save item's arranged position?

populating listview

string[] savedfiles; string datadr;  @override public void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_address);      datadr = getapplicationinfo().datadir;     showdirfile(datadr); }  void showdirfile(string dirpth) {     string path = dirpth+"/files";     log.d("files", "path: " + path);     file f = new file(path);     file file[] = f.listfiles();     log.d("files", "size: "+ file.length);      savedfiles = new string[file.length];     (int i=0; < file.length; i++)     {         log.d("files", "filename:" + file[i].getname());          savedfiles[i] = file[i].getname();     }      arrayadapter<string> adapter             = new arrayadapter<string>(this,             android.r.layout.simple_list_item_1,             savedfiles);     listview.setadapter(adapter); } 

to change item position , save them array

collections collections;  void positionchange(){      //to store arrays arraylist     list<string> newlist = new arraylist<string>(arrays.aslist(mydatafiles));      //to item's position @ first item in array if multiple arrays exist     string currentpos = string.valueof(intarraylist.get(0));     int oldpos = integer.valueof(currentpos);     int newpos = oldpos-1;      //swap position @ move list     collections.swap(newlist, oldpos, newpos);      //store arraylist data arrays     mydatafiles = newlist.toarray(mydatafiles);      intarraylist.clear();      adapter.notifydatasetchanged(); } 

edit

do note items in array filled datadr = getapplicationinfo().datadir;

perhaps need find way save arrangement position in directory?

as mentioned in comments, sharedpreferences trick. initialize in oncreate method.

// use member variable (private sharedpreferences prefs) prefs = this.getsharedpreferences("com.example.app", context.mode_private); 

since position of item may change, wise store file name instead of postion. place onitemselected (therefor have add listener listview).

listview.setonitemselectedlistener(new adapterview.onitemselectedlistener() {   @override   public void onitemselected(adapterview<?> parent, view view, int position, long id) {     prefs.edit().putstring("yourkey", listview.getitematposition(position)).apply();   } }); 

to set correct position after starting app have position of file in savedfile object.

loading string sharedpreferences:

string filename = prefs.getstring("yourkey", "");  

after initialization of listview , adapter iterate through list , compare strings. if string matches, take position , set listview object.

for(int = 0; < savedfiles.length; i++){   if(filename.equals(savedfiles[i])){     listview.setselection(i);     break;   } }