android - Getting NULL Pointer Exception while updating a Custom List View in Main Activity -

update 2

i have 3 class basically.for custom list view in main view.the problem while opening main activity getting null pointer exception , list not coming.first in main xml file.

  <?xml version="1.0" encoding="utf-8"?>  <relativelayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent" > 

  <button android:text="take (small) picture" android:id="@+id/btnintends"     android:layout_height="wrap_content"     android:layout_width="0dp"     android:layout_weight="1" />    </linearlayout>    <linearlayout    android:layout_width="match_parent"    android:layout_height="wrap_content"    android:layout_below="@+id/pic"    android:orientation="vertical" >     <textview        android:layout_width="match_parent"        android:layout_height="match_parent"        android:text="choose picture or video share"        android:gravity="center_horizontal"        android:textsize="18dp" /> 

<linearlayout   android:layout_width="match_parent"   android:id="@+id/imageview"   android:layout_height="300dp"   android:layout_gravity="center_vertical"   android:orientation="vertical" >  <imageview    android:layout_height="wrap_content"    android:layout_width="wrap_content"    android:layout_margintop="200dp"   android:visibility="visible"   android:id="@+id/imageview1" /> 

<linearlayout    android:layout_below="@id/imageview"   android:layout_height="wrap_content"   android:layout_width = "match_parent"   android:orientation="horizontal">    <listview       android:id="@+id/list"       android:layout_width="wrap_content"       android:layout_height="match_parent"       android:visibility="visible" />   </linearlayout>      </relativelayout> 

here list_item.xml

<relativelayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="fill_parent" android:layout_height="fill_parent" >   <textview     android:id="@+id/title"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_torightof="@+id/icon"     android:paddingbottom="10dp"     android:textcolor="#cc0033"     android:textsize="16dp" />  <textview     android:id="@+id/desc"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_below="@+id/title"     android:layout_torightof="@+id/icon"     android:paddingleft="10dp"     android:textcolor="#3399ff"     android:textsize="14dp" />   </relativelayout> 

as can see here xml have 2 buttons,one imageview , list view.now list gets updated main activity getting 2 things. 1.)a small text 2.)a large text

now in main activity oncreate method gets these 2 things local database.the data coming can see in mylogcat.so there no problem regarding database.so here goes oncreate method mainactivity.

  public void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.picactivity);      mydb = new dbhelper(picactivity.this);      try {         mydb.createdatabase(cont);     } catch (ioexception e) {         // todo auto-generated catch block         e.printstacktrace();     }     system.out.println("i in picactivity");      mimageview = (imageview) findviewbyid(r.id.imageview1);      mimagebitmap = null;       button picbtn = (button) findviewbyid(r.id.btnintend);     setbtnlistenerordisable(              picbtn,              mtakepiconclicklistener,             mediastore.action_image_capture     );      button picsbtn = (button) findviewbyid(r.id.btnintends);     setbtnlistenerordisable(              picsbtn,              mtakepicsonclicklistener,             mediastore.action_image_capture     );        if (build.version.sdk_int >= build.version_codes.froyo) {         malbumstoragedirfactory = new picalbumdirfactory();      } else {         malbumstoragedirfactory = new basealbumdirfactory();             }       mydb.opendatabase();       images = mydb.getimages();     description = mydb.getdescriptions();      location = mydb.getlocations();     int = images.size();     system.out.println("my database size"+i);     int k = 0;     if(i>0){     rowitems = new arraylist<rowitem>();      (int j = 0;j<i ; j++) {          system.out.println("loop value:--"+j);          system.out.println("location details:-----"+location.get(j));          system.out.println("description details:------"+description.get(j));              rowitem item = new rowitem(location.get(j), description.get(j));             rowitems.add(item);         }          listview = (listview) findviewbyid(r.id.list);          customlistviewadapter adapter = new customlistviewadapter(picactivity.this,                 r.layout.list_item, rowitems);          listview.setadapter(adapter);         listview.setonitemclicklistener(this);      } 

now listview onitemclick listner method like

     @override public void onitemclick(adapterview<?> parent, view view, int position, long id) {     toast toast = toast.maketext(getapplicationcontext(),             "item " + (position + 1) + ": " + rowitems.get(position),             toast.length_short);         toast.setgravity(gravity.bottom|gravity.center_horizontal, 0, 0);         toast.show();     } 

now there 2 other class.one rowitem class storing data row wise in list.that this

     public class rowitem {  private string title; private string desc;  public rowitem( string title, string desc) {      this.title = title;     this.desc = desc; }    public string getdesc() {     return desc; } public void setdesc(string desc) {     this.desc = desc; } public string gettitle() {     return title; } public void settitle(string title) {     this.title = title; } @override public string tostring() {     return title + "\n" + desc; }  } 

and lastly customlistview class........

public class customlistviewadapter extends arrayadapter<rowitem> {  context context; bitmap mybitmap;  public customlistviewadapter(context context, int resourceid,         list<rowitem> items) {     super(context, resourceid, items);     this.context = context; }   private class viewholder {      textview txttitle;     textview txtdesc; }  public view getview(int position, view convertview, viewgroup parent) {     viewholder holder = null;     rowitem rowitem = getitem(position);       layoutinflater minflater = (layoutinflater) context             .getsystemservice(activity.layout_inflater_service);     if (convertview == null) {         convertview = minflater.inflate(r.layout.list_item, null);         holder = new viewholder();         holder.txtdesc = (textview) convertview.findviewbyid(r.id.desc);         holder.txttitle = (textview) convertview.findviewbyid(r.id.title);          convertview.settag(holder);     } else         holder = (viewholder) convertview.gettag();      holder.txtdesc.settext(rowitem.getdesc());     holder.txttitle.settext(rowitem.gettitle());      return convertview; } } 

lastly logcat view..

      09-04 14:11:57.634: i/system.out(16814): context value:--com.cdotsys.photoapp.picactivity@421a24a0       09-04 14:11:57.639: i/system.out(16814): storage state:-mounted       09-04 14:11:57.639: i/system.out(16814): yes       09-04 14:11:57.639: i/system.out(16814): database path:--/storage/sdcard0/photoapp       09-04 14:11:57.639: i/system.out(16814): in picactivity       09-04 14:11:57.644: i/system.out(16814): database path:----/storage/sdcard0/photoapp/photodb       09-04 14:11:57.679: i/system.out(16814): database size1       09-04 14:11:57.684: i/system.out(16814): loop value:--0       09-04 14:11:57.684: i/system.out(16814): location details:-----vjgt       09-04 14:11:57.684: i/system.out(16814): description details:------gugf       09-04 14:11:57.714: d/androidruntime(16814): shutting down vm       09-04 14:11:57.714: w/dalvikvm(16814): threadid=1: thread exiting uncaught exception (group=0x417422a0)         09-04 14:34:57.834: e/androidruntime(18547): fatal exception: main        09-04 14:34:57.834: e/androidruntime(18547): java.lang.nullpointerexception        09-04 14:34:57.834: e/androidruntime(18547):     @ com.cdotsys.adapters.customlistviewadapter.getview(customlistviewadapter.java:56)          09-04 14:11:57.764: e/androidruntime(16814): fatal exception: main       09-04 14:11:57.764: e/androidruntime(16814): java.lang.nullpointerexception       09-04 14:11:57.764: e/androidruntime(16814):  @ java.io.file.fixslashes(file.java:185)       09-04 14:11:57.764: e/androidruntime(16814):  @ java.io.file.<init>(file.java:134)        09-04 14:11:57.764: e/androidruntime(16814):  @ android.widget.abslistview.obtainview(abslistview.java:2465)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.widget.listview.measureheightofchildren(listview.java:1250)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.widget.listview.onmeasure(listview.java:1162)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.view.view.measure(view.java:15504)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.view.viewgroup.measurechildwithmargins(viewgroup.java:5059)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.widget.linearlayout.measurechildbeforelayout(linearlayout.java:1396)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.widget.linearlayout.measurehorizontal(linearlayout.java:1038)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.widget.linearlayout.onmeasure(linearlayout.java:576)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.view.view.measure(view.java:15504)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.widget.relativelayout.measurechild(relativelayout.java:602)      09-04 14:11:57.764: e/androidruntime(16814):   @  android.widget.relativelayout.onmeasure(relativelayout.java:415)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.view.view.measure(view.java:15504)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.view.viewgroup.measurechildwithmargins(viewgroup.java:5059)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.widget.framelayout.onmeasure(framelayout.java:310)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.view.view.measure(view.java:15504)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.widget.linearlayout.measurevertical(linearlayout.java:833)       09-04 14:11:57.764: e/androidruntime(16814):  @ android.widget.linearlayout.onmeasure(linearlayout.java:574)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.view.view.measure(view.java:15504)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.view.viewgroup.measurechildwithmargins(viewgroup.java:5059)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.widget.framelayout.onmeasure(framelayout.java:310)     09-04 14:11:57.764: e/androidruntime(16814):    @ com.android.internal.policy.impl.phonewindow$decorview.onmeasure(phonewindow.java:2385)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.view.view.measure(view.java:15504)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.view.viewrootimpl.performmeasure(viewrootimpl.java:1979)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.view.viewrootimpl.measurehierarchy(viewrootimpl.java:1222)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.view.viewrootimpl.performtraversals(viewrootimpl.java:1395)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.view.viewrootimpl.dotraversal(viewrootimpl.java:1115)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.view.viewrootimpl$traversalrunnable.run(viewrootimpl.java:4526)      09-04 14:11:57.764: e/androidruntime(16814):   @ android.view.choreographer$callbackrecord.run(choreographer.java:725)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.view.choreographer.docallbacks(choreographer.java:555)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.view.choreographer.doframe(choreographer.java:525)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.view.choreographer$framedisplayeventreceiver.run(choreographer.java:711)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.os.handler.handlecallback(handler.java:615)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.os.handler.dispatchmessage(handler.java:92)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.os.looper.loop(looper.java:137)     09-04 14:11:57.764: e/androidruntime(16814):    @ android.app.activitythread.main(activitythread.java:4921)     09-04 14:11:57.764: e/androidruntime(16814):    @ java.lang.reflect.method.invokenative(native method)    09-04 14:11:57.764: e/androidruntime(16814):     @ java.lang.reflect.method.invoke(method.java:511)    09-04 14:11:57.764: e/androidruntime(16814):     @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1027)    09-04 14:11:57.764: e/androidruntime(16814):     @ com.android.internal.os.zygoteinit.main(zygoteinit.java:794)    09-04 14:11:57.764: e/androidruntime(16814):     @ dalvik.system.nativestart.main(native method) 

here can see there no problem regarding database.there problem regarding upgrading views guess.please me.please !! how can rid of null pointer exception happening in main thread.kindly please me.its quite bothering me quite amount of time :(

    please check        @override                 public int getcount() {                     if (arr == null )                          return 0;                     return arr.size();                 }           @override         public object getitem(int arg0) {             if (arr == null)                  return null;              else                  return arr.get(arg0);         }  , check null value in getview