ListView android and null pointer exception -


i'm trying show simple listview ,but have problems .it seems had nullpointerexception . here's xml :

 <linearlayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingleft="@dimen/activity_horizontal_margin" android:paddingright="@dimen/activity_horizontal_margin" android:paddingtop="@dimen/activity_vertical_margin" android:paddingbottom="@dimen/activity_vertical_margin" tools:context=".mainactivity">  <listview     android:layout_width="fill_parent"     android:layout_height="fill_parent"     android:id="@+id/listview"     />

and main class :

 public class mainactivity extends activity {  private list<string> exemple; private listview liste=(listview) findviewbyid(r.id.listview);   protected void oncreate(bundle savedinstancestate) {      super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);     exemple=new arraylist<string>();      exemple.add("item 1");     exemple.add("item 2");     exemple.add("item 3");      arrayadapter<string> adapter = new arrayadapter<string>(this, android.r.layout.simple_list_item_1, exemple);     liste.setadapter(adapter); } }

i got error :

07-07 11:59:27.024    2758-2758/tunisia_sat.com.essai e/androidruntime﹕ fatal exception: main     process: tunisia_sat.com.essai, pid: 2758     java.lang.runtimeexception: unable instantiate activity componentinfo{tunisia_sat.com.essai/tunisia_sat.com.essai.mainactivity}: java.lang.nullpointerexception

move liste initialization after setcontentview:

setcontentview(r.layout.activity_main); liste = (listview) findviewbyid(r.id.listview);

why nullpointerexception?
calling ssetadapter on null reference liste in following line:

liste.setadapter(adapter);

liste null because being initialized before view up(binding activity view). so, findviewbyid returns null.


Comments

Post a Comment

Popular posts from this blog

android - Pass an Serializable object in AIDL -

i have defined aidl file interface imyfeature { void dotask(class clazz); } but need pass class object process. possible in android? if so, how? i tried: interface imyfeature { serializable class; void dotask(class clazz); } but doesn’t work. aidl in android supports custom class implement parcelable interface. in case want send class object not possible. can send class canonical name , retrieve in service. for example have aidl file interface imyfeature { void dotask(string classname); } then call : binder.dotask(myclass.class.getcanonicalname()); and in service binder stub implementation : private final imyfeature mbinder = new imyfeature.stub() { public void dotask(string classname) { try { class<?> clazz = class.forname(classname); constructor<?> ctor = clazz.getconstructor((class[]) null); object object = ctor.newinstance(); ...
Read more

How to provide Authorization & Authentication using Asp.net, C#? -

Image
i have asp.net application in c#. i have provide page authorization specific user/usergroup. i have created 2 tables in database: 1) pagename 2)permissions[insert, update, view, delete] but i'm unable match tables , permissions assigning... can 1 please me, how created tables in database , how coding. please me. you can below explanation. configure access specific file , folder, set forms-based authentication. request page in application redirected logon.aspx automatically. in web.config file, type or paste following code. this code grants users access default1.aspx page , subdir1 folder . <configuration> <system.web> <authentication mode="forms" > <forms loginurl="login.aspx" name=".aspnetauth" protection="none" path="/" timeout="20" > </forms> </authentication> <!-- section denies access files in...
Read more

How to use Authorization & Authentication in Asp.net, C#? -

i using roll management , trying give page , folder access according user or user group, using server created ad group user authentication. i have default1.aspx page default , subdir1 folder give different access separate user group i using below logic in web.config. <location path="subdir1"> <system.web> <authorization> <allow users ="?" /> </authorization> </system.web> </location> i facing problem provide same access 2 or more directory same user should have provide allow user code twice both folder? i can use logic repeating value folder want access providing in 1 logic. i have got answer configure folder/page access, have make different access shown below.. configure access specific file , folder, set forms-based authentication. request page in application redirected logon.aspx automatically. in web.config file, done following code. this code grants user...
Read more