android - How can I get view from ListView by position and set text to item? -

i trying implement custom list. there textview in each row, want set text textview oncreate in following way nullpointer exception.

my custom list

public class customlist extends arrayadapter<string>{  private final activity context; private final string[] web; private final integer[] imageid;   textview txttitle;  public customlist(activity context, string[] web, integer[] imageid) { super(context, r.layout.list_single, web); this.context = context; this.web = web; this.imageid = imageid; }   @override public view getview(int position, view view, viewgroup parent) {  layoutinflater inflater = context.getlayoutinflater(); view rowview= inflater.inflate(r.layout.list_single, null, true); imageview imageview = (imageview) rowview.findviewbyid(r.id.img);  txttitle = (textview) rowview.findviewbyid(r.id.txt);  txttitle.settext(web[position]); txttitle.settext("menjar ali");   imageview.setimageresource(imageid[position]); return rowview; }     } 

my main activity:

public class mainactivity extends activity {  listview list;    string[] web = {     "google plus",       "twitter",       "windows"    } ;    integer[] imageid = {       r.drawable.ic_launcher,       r.drawable.ic_launcher,       r.drawable.ic_launcher    }; textview mytextview;  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);      customlist adapter = new customlist(mainactivity.this, web, imageid);      list=(listview)findviewbyid(r.id.list);      list.setadapter(adapter);       view vv = list.getchildat(0);      textview tt = (textview)vv.findviewbyid(r.id.txt);     tt.settext("momomo");                        //here error } 

my list_single.xml

<?xml version="1.0" encoding="utf-8"?> <tablelayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" > <tablerow>     <imageview         android:id="@+id/img"         android:layout_width="50dp"         android:layout_height="50dp"/>     <textview         android:id="@+id/txt"         android:layout_width="wrap_content"         android:layout_height="50dp" /> </tablerow> </tablelayout> 

actually, trying implement single row listview edittext instead of edittext inside scrollview have better way of scrolling funtionality, , facing various problem in doing that.

so if have precise example edittext(inside listview) can accessed anywhere in main_activity , efficiently perform operatiopn settet, gettext, color change etc, helpful.

if want change color , value implement onitemclick of listview here vv null because position passing wrong.

in custom adapter comment out line txttitle.settext("menjar ali"); because before assigned value web array , again set value menjar ali. so, show menjar ali every row item.

code snippet

activity

public class mainactivity extends activity {  listview list;    string[] web = {     "google plus",       "twitter",       "windows"    } ;    integer[] imageid = {       r.drawable.ic_launcher,       r.drawable.ic_launcher,       r.drawable.ic_launcher    }; textview mytextview;  @override protected void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);      customlist adapter = new customlist(mainactivity.this, web, imageid);      list=(listview)findviewbyid(r.id.list);      list.setadapter(adapter); } 

list_single.xml

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:orientation="horizontal"     android:gravity="center_vertical" >      <imageview         android:id="@+id/img"         android:layout_width="50dp"         android:layout_height="50dp"         android:adjustviewbounds="true"         android:croptopadding="false"         android:scaletype="fitxy"         android:src="@drawable/ic_launcher" />      <textview         android:id="@+id/txt"         android:layout_width="0dp"         android:layout_height="wrap_content"         android:layout_weight="1"         android:layout_marginleft="12dp"         android:text="text" />  </linearlayout> 

adapter

public class customlist extends arrayadapter<string>{  private final activity context; private final string[] web; private final integer[] imageid;   textview txttitle;  public customlist(activity context, string[] web, integer[] imageid) { super(context, r.layout.list_single, web); this.context = context; this.web = web; this.imageid = imageid; }   @override public view getview(int position, view view, viewgroup parent) { viewholder viewholder; if(view == null) {   layoutinflater inflater = (layoutinflater) context.getsystemservice(context.layout_inflater_service);   view = inflater.inflate(r.layout.list_single, parent, false);   viewholder = new viewholder();   viewholder.imageview = (imageview) view.findviewbyid(r.id.img);   viewholder.txttitle = (textview) view.findviewbyid(r.id.txt);   view.settag(viewholder); } else {   viewholder = (viewholder) view.gettag(); }  viewholder.txttitle.settext(web[position]); viewholder.imageview.setimageresource(imageid[position]); return view; }  private class viewholder {  textview txttitle;  imageview imageview; } } 

if want change textcolor can change in click event i.e click on textview or onitemclick of listview.

in case of changing data have modify values inside web array