Android - ListView refresh/update from the Main Activity where it is called -

i have application lists values of product variant, unit, , quantity.

i have activity listview shown:

public class orderform extends activity {      @override     public void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_order_form);          arraylist image_details = getlistdata();         final listview lv1 = (listview) findviewbyid(r.id.custom_list);         lv1.setadapter(new customlistadapter(this, image_details));       }      private arraylist getlistdata() {          arraylist results = new arraylist();         orderdetailsclass orderdata = new orderdetailsclass();          return results;     }      public void onadditem(view view){          arraylist results = new arraylist();         orderdetailsclass orderdata = new orderdetailsclass();          orderdata = new orderdetailsclass();         orderdata.setvariants("flavored");         orderdata.setunit("cans");         orderdata.setquantity(1);         results.add(orderdata);          //selectvariant();         //selectunit();         //selectquantity();      } } 

this customadapter

public class customlistadapter extends baseadapter {    private arraylist<orderdetailsclass> listdata;    private layoutinflater layoutinflater;        public customlistadapter(context context, arraylist<orderdetailsclass> listdata) {     this.listdata = listdata;     layoutinflater = layoutinflater.from(context);   }    @override   public int getcount() {     return listdata.size();   }    @override   public object getitem(int position) {     return listdata.get(position);   }    @override   public long getitemid(int position) {     return position;   }    public view getview(int position, view convertview, viewgroup parent) {     viewholder holder;     if (convertview == null) {         convertview = layoutinflater.inflate(r.layout.list_row_layout, null);         holder = new viewholder();         holder.variantview = (textview) convertview.findviewbyid(r.id.variant);         holder.unitview = (textview) convertview.findviewbyid(r.id.unit);         holder.quantityview = (textview) convertview.findviewbyid(r.id.quantity);         convertview.settag(holder);     } else {         holder = (viewholder) convertview.gettag();     }      holder.variantview.settext(listdata.get(position).getvariants());     holder.unitview.settext("by, " + listdata.get(position).getunit());     holder.quantityview.settext(string.valueof(listdata.get(position).getquantity()));      return convertview; }  static class viewholder {     textview variantview;     textview unitview;     textview quantityview; }    public void updateresults(arraylist<orderdetailsclass> results) {     listdata = results;       //triggers list update       notifydatasetchanged();   }  } 

this list_row_layout

<?xml version="1.0" encoding="utf-8"?> <relativelayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" >  <!--  android:minheight="50dp" android:orientation="horizontal" android:padding="5dip"   -->  <textview     android:id="@+id/variant"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_alignparentleft="true"     android:layout_alignparenttop="true"     android:text="variant" />  <textview     android:id="@+id/unit"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_alignparenttop="true"     android:layout_centerhorizontal="true"     android:text="unit" />  <textview     android:id="@+id/quantity"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_alignparentright="true"     android:layout_alignparenttop="true"     android:text="quantity" />  </relativelayout> 

this activity_order_form

<?xml version="1.0" encoding="utf-8"?>  <relativelayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" android:orientation="vertical">  <listview     android:id="@+id/custom_list"     android:layout_width="fill_parent"     android:layout_height="386dp"     android:dividerheight="1dp" />  <button     android:id="@+id/button1"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_alignparentbottom="true"     android:layout_centerhorizontal="true"     android:onclick="onadditem"     android:text="add" />  </relativelayout> 

what want when press onadditem function, after data has been added, listview refresh , display changes. far, i've seen notifydatasetchanged() being used in baseadapter class. i've tried seems notifydatasetchanged() should called within baseadapter, want able refresh orderform activity.

any ideas?

thanks.

keep reference customadapter in orderform activity:

public class orderform extends activity {  customlistadapter customlistadapter;  @override public void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_order_form);      arraylist image_details = getlistdata();     final listview lv1 = (listview) findviewbyid(r.id.custom_list);     customlistadapter = new customlistadapter(this, image_details);     lv1.setadapter(customlistadapter); } 

then can call customadapter.notifydatasetchanged(). public method on adapter can call activity fine.