android - custom layout with child -

i facing problem.

i created custom layout.

i need expand , collapse these childview on click of expandable layout. how can expandable view's in sample app.

i want add child in expandable view ,can not use of activity set child every thing in expandableview class.

//myactivity layout custom layout

<scrollview xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:custom="http://schemas.android.com/apk/res/com.example.customview"     xmlns:tools="http://schemas.android.com/tools"     android:layout_width="match_parent"     android:layout_height="fill_parent" >      <linearlayout         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:orientation="vertical" >          <com.example.customview.expandableview             android:id="@+id/ex_view1"             android:layout_width="match_parent"             android:layout_height="wrap_content"             custom:buttontitle="details"             custom:title="all staff details"             custom:visibility="@integer/visible"              android:orientation="vertical">         </com.example.customview.expandableview>          <com.example.customview.expandableview             android:id="@+id/ex_view2"             android:layout_width="match_parent"             android:layout_height="wrap_content"             custom:title="next coming"             custom:visibility="@integer/gone" />          <com.example.customview.expandableview             android:id="@+id/ex_view3"             android:layout_width="match_parent"             android:layout_height="wrap_content"             custom:title="previous record"             custom:visibility="@integer/gone" />          <com.example.customview.expandableview             android:id="@+id/ex_view4"             android:layout_width="match_parent"             android:layout_height="wrap_content"             custom:buttontitle="next"             custom:title="new news"             custom:visibility="@integer/visible" />     </linearlayout>  </scrollview> 

// mainlayout

<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:orientation="vertical" >      <linearlayout         android:id="@+id/parent_id"         android:layout_width="match_parent"         android:layout_height="wrap_content"         android:background="#aaabab"         android:orientation="horizontal" >          <textview             android:id="@+id/tv_text"             android:layout_width="0dp"             android:layout_height="wrap_content"             android:layout_gravity="center_vertical"             android:layout_weight="1"             android:paddingbottom="15dp"             android:paddingtop="15dp"             android:textsize="18sp"             android:textstyle="bold" />          <button             android:id="@+id/btn"             android:layout_width="wrap_content"             android:layout_height="wrap_content"             android:layout_gravity="center_vertical"             android:background="#b7b7b8"             android:drawableleft="@drawable/ic_menu_edit"             android:paddingright="5dp" />      </linearlayout>      <view         android:layout_width="match_parent"         android:layout_height="5dp" />  </linearlayout> 

//code

public class expandableview extends linearlayout  {     textview textview;     button button;     linearlayout parentlinear,childlinear;     view view,convertview;     context context;     webview web;     layoutinflater inflater ;     view viewlay ;       /**      * constructor      * @param context      * @param attr      */     public expandableview(final context context,attributeset attr)      {         super(context,attr);         this.context = context;         inflate(context,r.layout.mainlayout, this);         textview =(textview)findviewbyid(r.id.tv_text);         button = (button)findviewbyid(r.id.btn);         parentlinear =(linearlayout)findviewbyid(r.id.parent_id);         getattributes(attr);         //setchildview();  }      public void setchildview()     {         web = (webview)findviewbyid(r.id.webview);         web.loadurl("file:///android_asset/info.html");     }      /**      * function attributes attrs.xml      * @param attr      */     public void getattributes(attributeset attr)     {         typedarray attributes = context.obtainstyledattributes(attr,r.styleable.mycustomwidget);          string texttitle = attributes.getstring(r.styleable.mycustomwidget_title);         textview.settext(texttitle);          string textbuttontitle = attributes.getstring(r.styleable.mycustomwidget_buttontitle);         button.settext(textbuttontitle);          int visibility = attributes.getinteger(r.styleable.mycustomwidget_visibility, 0);         button.setvisibility(visibility);          attributes.recycle();     }  } 

now need add web view inside custom layout,so doing this

 <com.example.customview.expandableview             android:id="@+id/ex_view1"             android:layout_width="match_parent"             android:layout_height="wrap_content"             custom:buttontitle="details"             custom:title="all staff details"             custom:visibility="@integer/visible"              android:orientation="vertical">           <webview                 android:id="@+id/webview"                 android:layout_width="match_parent"                 android:layout_height="wrap_content" />          </com.example.customview.expandableview> 

problem case 1:-

if setting child webview in activity ,its working fine.i.e

//activity class

expandableone = (expandableview)findviewbyid(r.id.ex_view1);          expandableone.setchildview(); 

but don't want set child in activity.

case 2:- want set in expandableview class

so calling method in constructor .

setchildview();//this in constructor

and remove expandableone.setchildview(); activity class....now crashing

my logcat

05-03 11:07:29.364: e/androidruntime(1336): fatal exception: main 05-03 11:07:29.364: e/androidruntime(1336): java.lang.runtimeexception: unable start activity componentinfo{com.example.customview/com.example.customview.expandableactivity}: android.view.inflateexception: binary xml file line #12: error inflating class com.example.customview.expandableview 05-03 11:07:29.364: e/androidruntime(1336):     @ android.app.activitythread.performlaunchactivity(activitythread.java:1956) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.app.activitythread.handlelaunchactivity(activitythread.java:1981) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.app.activitythread.access$600(activitythread.java:123) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.app.activitythread$h.handlemessage(activitythread.java:1147) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.os.handler.dispatchmessage(handler.java:99) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.os.looper.loop(looper.java:137) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.app.activitythread.main(activitythread.java:4424) 05-03 11:07:29.364: e/androidruntime(1336):     @ java.lang.reflect.method.invokenative(native method) 05-03 11:07:29.364: e/androidruntime(1336):     @ java.lang.reflect.method.invoke(method.java:511) 05-03 11:07:29.364: e/androidruntime(1336):     @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:784) 05-03 11:07:29.364: e/androidruntime(1336):     @ com.android.internal.os.zygoteinit.main(zygoteinit.java:551) 05-03 11:07:29.364: e/androidruntime(1336):     @ dalvik.system.nativestart.main(native method) 05-03 11:07:29.364: e/androidruntime(1336): caused by: android.view.inflateexception: binary xml file line #12: error inflating class com.example.customview.expandableview 05-03 11:07:29.364: e/androidruntime(1336):     @ android.view.layoutinflater.createview(layoutinflater.java:606) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.view.layoutinflater.createviewfromtag(layoutinflater.java:680) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.view.layoutinflater.rinflate(layoutinflater.java:739) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.view.layoutinflater.rinflate(layoutinflater.java:742) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.view.layoutinflater.inflate(layoutinflater.java:489) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.view.layoutinflater.inflate(layoutinflater.java:396) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.view.layoutinflater.inflate(layoutinflater.java:352) 05-03 11:07:29.364: e/androidruntime(1336):     @ com.android.internal.policy.impl.phonewindow.setcontentview(phonewindow.java:251) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.app.activity.setcontentview(activity.java:1835) 05-03 11:07:29.364: e/androidruntime(1336):     @ com.example.customview.expandableactivity.oncreate(expandableactivity.java:23) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.app.activity.performcreate(activity.java:4465) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1049) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.app.activitythread.performlaunchactivity(activitythread.java:1920) 05-03 11:07:29.364: e/androidruntime(1336):     ... 11 more 05-03 11:07:29.364: e/androidruntime(1336): caused by: java.lang.reflect.invocationtargetexception 05-03 11:07:29.364: e/androidruntime(1336):     @ java.lang.reflect.constructor.constructnative(native method) 05-03 11:07:29.364: e/androidruntime(1336):     @ java.lang.reflect.constructor.newinstance(constructor.java:417) 05-03 11:07:29.364: e/androidruntime(1336):     @ android.view.layoutinflater.createview(layoutinflater.java:586) 05-03 11:07:29.364: e/androidruntime(1336):     ... 23 more 05-03 11:07:29.364: e/androidruntime(1336): caused by: java.lang.nullpointerexception 05-03 11:07:29.364: e/androidruntime(1336):     @ com.example.customview.expandableview.setchildview(expandableview.java:48) 05-03 11:07:29.364: e/androidruntime(1336):     @ com.example.customview.expandableview.<init>(expandableview.java:41) 05-03 11:07:29.364: e/androidruntime(1336):     ... 26 more 

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case 3:-