android - Adapter error while running code -

i new android development , working on listview .. code not have error when try run it, application crashes.

this mainactivity code:

package com.example.view;  import java.util.arraylist;  import android.app.activity; import android.os.bundle; import android.widget.listview;  public class mainactivity extends activity {  listview lv; arraylist<listviewitem> items; customlistviewadapter adapter;  @override public void oncreate(bundle savedinstancestate) {     super.oncreate(savedinstancestate);     setcontentview(r.layout.activity_main);      lv = (listview) findviewbyid(r.id.listview);     items = new arraylist<mainactivity.listviewitem>();     items.add(new listviewitem(r.drawable.ic_launcher, "item1", "item1 description"));     items.add(new listviewitem(r.drawable.ic_launcher, "item2", "item2 description"));     items.add(new listviewitem(r.drawable.ic_launcher, "item3", "item3 description"));     items.add(new listviewitem(r.drawable.ic_launcher, "item4", "item4 description"));     adapter = new customlistviewadapter(this, items);     lv.setadapter(adapter); }  class listviewitem {     private int thumbnailresource;     private string title;     private string subtitle;      public listviewitem()     {      }      public listviewitem(int thumbnailresource, string title, string subtitle)     {         this.thumbnailresource = thumbnailresource;         this.title = title;         this.subtitle = subtitle;     }      public int getthumbnailresource()     {         return thumbnailresource;     }      public void setthumbnailresource(int thumbnailresource)     {         this.thumbnailresource = thumbnailresource;     }      public string gettitle()     {         return title;     }      public void settitle(string title)     {         this.title = title;     }      public string getsubtitle()     {         return subtitle;     }      public void setsubtitle(string subtitle)     {         this.subtitle = subtitle;     }  } } 

and adapter class:

package com.example.view;  import java.util.arraylist;  import android.app.activity; import android.content.context; import android.view.layoutinflater; import android.view.view; import android.view.viewgroup; import android.widget.arrayadapter; import android.widget.checkbox; import android.widget.imageview; import android.widget.textview;  import com.example.view.mainactivity.listviewitem;  public class customlistviewadapter extends arrayadapter<listviewitem> { layoutinflater inflater; arraylist<listviewitem> items;  public customlistviewadapter(activity context, arraylist<listviewitem> items) {       super(context, r.layout.list_item_row, items);      this.items = items;     this.inflater = (layoutinflater)context.getsystemservice(context.layout_inflater_service); }  public view getview(final int position, view convertview, viewgroup parent) {        listviewitem item = items.get(position);     view rowview = inflater.inflate(r.layout.list_item_row, parent, false);      imageview imgview = (imageview) rowview.findviewbyid(r.id.imgthumbnail);     textview txttitle = (textview) rowview.findviewbyid(r.id.txttitle);     textview txtsubtitle = (textview) rowview.findviewbyid(r.id.txtsubtitle);     checkbox chkbox = (checkbox) rowview.findviewbyid(r.id.checkbox);      imgview.setimageresource(item.getthumbnailresource());     txttitle.settext(item.gettitle());     txtsubtitle.settext(item.getsubtitle());      return rowview;   } } 

and xml file row

<relativelayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:android1="http://schemas.android.com/apk/res/android" android:id="@+id/relativelayout1" android:layout_width="fill_parent" android:layout_height="fill_parent" android:padding="5dip" >  <imageview        android:layout_width="78dip"        android:layout_height="78dip"        android:id="@+id/imgthumbnail"        android:layout_alignparentleft="true"       android:layout_centerinparent="true"     android:layout_marginleft="-3dip"     android:scaletype="centerinside">   </imageview>    <textview        android:textappearance="?android:attr/textappearancelarge"        android:layout_height="wrap_content"        android:text="textview"        android:layout_width="wrap_content"        android:id="@+id/txttitle"        android:layout_torightof="@+id/imgthumbnail"     android:layout_margintop="6dip"       android:layout_marginleft="6dip">   </textview>    <textview        android:layout_height="wrap_content"        android:text="textview"        android:layout_width="wrap_content"        android:id="@+id/txtsubtitle"        android:layout_torightof="@+id/imgthumbnail"       android:layout_below="@+id/txttitle"     android:layout_margintop="3dip"       android:layout_marginleft="6dip">   </textview>  <listview     android1:id="@+id/listview"     android1:layout_width="match_parent"     android1:layout_height="wrap_content"     android1:layout_alignleft="@+id/imgthumbnail"     android1:layout_aligntop="@+id/txttitle"     android1:layout_marginleft="17dp" > </listview>  <checkbox     android:id="@+id/checkbox"     android:layout_width="wrap_content"     android:layout_height="wrap_content"     android:layout_alignparentright="true"     android:layout_marginleft="4px"     android:layout_marginright="10px" />  </relativelayout> 

and logcat errors

06-27 14:59:38.748: e/moreinfohpw_viewgroup(11621): parent view not textview 06-27 14:59:38.773: e/androidruntime(11621): fatal exception: main 06-27 14:59:38.773: e/androidruntime(11621): process: com.example.view, pid: 11621 06-27 14:59:38.773: e/androidruntime(11621): java.lang.runtimeexception: unable start     activity componentinfo{com.example.view/com.example.view.mainactivity}:     java.lang.nullpointerexception 06-27 14:59:38.773: e/androidruntime(11621):    @     android.app.activitythread.performlaunchactivity(activitythread.java:2282) 06-27 14:59:38.773: e/androidruntime(11621):    @     android.app.activitythread.handlelaunchactivity(activitythread.java:2340) 06-27 14:59:38.773: e/androidruntime(11621):    @     android.app.activitythread.access$800(activitythread.java:157) 06-27 14:59:38.773: e/androidruntime(11621):    @     android.app.activitythread$h.handlemessage(activitythread.java:1247) 06-27 14:59:38.773: e/androidruntime(11621):    @     android.os.handler.dispatchmessage(handler.java:102) 06-27 14:59:38.773: e/androidruntime(11621):    @ android.os.looper.loop(looper.java:157) 06-27 14:59:38.773: e/androidruntime(11621):    @     android.app.activitythread.main(activitythread.java:5293) 06-27 14:59:38.773: e/androidruntime(11621):    @     java.lang.reflect.method.invokenative(native method) 06-27 14:59:38.773: e/androidruntime(11621):    @     java.lang.reflect.method.invoke(method.java:515) 06-27 14:59:38.773: e/androidruntime(11621):    @     com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:1265) 06-27 14:59:38.773: e/androidruntime(11621):    @     com.android.internal.os.zygoteinit.main(zygoteinit.java:1081) 06-27 14:59:38.773: e/androidruntime(11621):    @ dalvik.system.nativestart.main(native     method) 06-27 14:59:38.773: e/androidruntime(11621): caused by: java.lang.nullpointerexception 06-27 14:59:38.773: e/androidruntime(11621):    @     com.example.view.mainactivity.oncreate(mainactivity.java:27) 06-27 14:59:38.773: e/androidruntime(11621):    @     android.app.activity.performcreate(activity.java:5389) 06-27 14:59:38.773: e/androidruntime(11621):    @     android.app.instrumentation.callactivityoncreate(instrumentation.java:1105) 06-27 14:59:38.773: e/androidruntime(11621):    @     android.app.activitythread.performlaunchactivity(activitythread.java:2246) 06-27 14:59:38.773: e/androidruntime(11621):    ... 11 more 

you getting error on line lv.setadapter(adapter);

i sure listview not present in activity_main.xml layout file.

you have put listview in activity_main.xml file.

you added listview mistake in layout of row file.