android - Custom Expandablelistview unsorting data -

i have expandable listview data, stored in list , in hashmap. problem expandable listview showing data unsorted when collapse , expand group. i'm going crazy!!!

import java.util.arrays; import java.util.hashmap; import java.util.hashset; import java.util.list; import java.util.set;  import android.content.context; import android.graphics.color; import android.graphics.typeface; import android.view.layoutinflater; import android.view.view; import android.view.viewgroup; import android.widget.baseexpandablelistadapter; import android.widget.filter; import android.widget.linearlayout; import android.widget.textview;  import com.pebbo.yaa.r;  public class customexpandablelistadapter extends baseexpandablelistadapter {      private context _context;     private list<pojoalgcat> _listdataheader; // header titles     // child data in format of header title, child title     private hashmap<pojoalgcat, list<pojoalg>> _listdatachild;      integer[] algs_lite = {5, 19};     integer[] algs_cat_lite = {1, 2};      linearlayout ll_row, ll_row_child;     textview lbllistheader;     textview txtlistchild;      public customexpandablelistadapter(context context, list<pojoalgcat> listdataheader,                                        hashmap<pojoalgcat, list<pojoalg>> listchilddata) {         this._context = context;         this._listdataheader = listdataheader;         this._listdatachild = listchilddata;     }      @override     public object getchild(int groupposition, int childposititon) {         return this._listdatachild.get(this._listdataheader.get(groupposition))                 .get(childposititon);     }      public object getchildtitle(int groupposition, int childposititon) {         return this._listdatachild.get(this._listdataheader.get(groupposition)).get(childposititon).getname();     }      @override     public long getchildid(int groupposition, int childposition) {         return this._listdatachild.get(this._listdataheader.get(groupposition)).get(childposition).getid();     }      public int getcatid(int groupposition) {         return this._listdataheader.get(groupposition).getid();     }      public int getalgid(int groupposition, int childposition) {         return this._listdatachild.get(this._listdataheader.get(groupposition)).get(childposition).getid();     }      @override     public view getchildview(int groupposition, final int childposition,                              boolean islastchild, view convertview, viewgroup parent) {          final string childtext = (string) getchildtitle(groupposition, childposition);          boolean exists = containsvalue(algs_lite, getalgid(groupposition, childposition));          if (convertview == null) {             layoutinflater infalinflater = (layoutinflater) this._context.getsystemservice(context.layout_inflater_service);             convertview = infalinflater.inflate(r.layout.list_item, null);              ll_row_child = (linearlayout) convertview.findviewbyid(r.id.ll_row_child);             txtlistchild = (textview) convertview.findviewbyid(r.id.lbllistitem);              if(exists){                 //log.i("adapter1", "value:::" + exists + ":::id:::" + f.getid() + ":::name:::" + f.getname() + ":::disponible");                 ll_row_child.setbackgroundcolor(color.white);                 txtlistchild.settextcolor(_context.getresources().getcolor(r.color.darkbluebg));             }else{                 //log.e("adapter1", "value:::" + exists + ":::id:::" + f.getid() + ":::name:::" + f.getname() + ":::no disponible");                 ll_row_child.setbackgroundcolor(color.ltgray);                 txtlistchild.settextcolor(color.gray);              }         }          txtlistchild.settext(childtext);         return convertview;     }      @override     public int getchildrencount(int groupposition) {         return this._listdatachild.get(this._listdataheader.get(groupposition))                 .size();     }      @override     public object getgroup(int groupposition) {         return this._listdataheader.get(groupposition);     }      public object getgrouptitle(int groupposition) {         return this._listdataheader.get(groupposition).getcategory();     }      @override     public int getgroupcount() {         return this._listdataheader.size();     }      @override     public long getgroupid(int groupposition) {         return this._listdataheader.get(groupposition).getid();     }      @override     public view getgroupview(int groupposition, boolean isexpanded,                              view convertview, viewgroup parent) {         string headertitle = (string) getgrouptitle(groupposition);          boolean exists_alg = containsvalue(algs_cat_lite, getcatid(groupposition));          if (convertview == null) {             layoutinflater infalinflater = (layoutinflater) this._context                     .getsystemservice(context.layout_inflater_service);             convertview = infalinflater.inflate(r.layout.list_group, null);              ll_row = (linearlayout) convertview.findviewbyid(r.id.ll_row);             lbllistheader = (textview) convertview.findviewbyid(r.id.lbllistheader);              if(exists_alg){                 //log.i("adapter1", "value:::" + exists + ":::id:::" + f.getid() + ":::name:::" + f.getname() + ":::disponible");                 ll_row.setbackgroundcolor(_context.getresources().getcolor(r.color.bluebg));                 lbllistheader.settextcolor(color.white);             }else{                 //log.e("adapter1", "value:::" + exists + ":::id:::" + f.getid() + ":::name:::" + f.getname() + ":::no disponible");                 ll_row.setbackgroundcolor(_context.getresources().getcolor(r.color.dimgray));                 lbllistheader.settextcolor(_context.getresources().getcolor(r.color.lightgrey));             }         }          lbllistheader.settext(headertitle);          return convertview;     }      @override     public boolean hasstableids() {         return false;     }      @override     public boolean ischildselectable(int groupposition, int childposition) {         return true;     }      public static boolean containsvalue(integer[] arr, integer targetvalue) {         set<integer> set = new hashset<integer>(arrays.aslist(arr));         return set.contains(targetvalue);     } } 

what i'm doing wrong?? :(