EditTexts and ListView Practice in android not working -

i have made simple android app 2 activity..in 1st 3 edittexts , 2 button "insert" , "cancel" there , in second activity listview.i want when insert button of ctivity1 pressed values entered in 3 of edittexts 1st acitivity should go 2nd activity , display in simple listview...i have tried following code not working...emulator shows "unfortunately app stopped"..

mainactivity.java

package com.example.listdemo;  import java.util.arraylist;  import android.r.id; import android.os.bundle; import android.app.activity; import android.content.intent; import android.view.menu; import android.view.view; import android.view.view.onclicklistener; import android.widget.arrayadapter; import android.widget.button; import android.widget.edittext;  public class mainactivity extends activity { button b1,b2; edittext e1,e2,e3;     @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);          final edittext e1=(edittext)findviewbyid(r.id.edittext1);         final edittext e2=(edittext)findviewbyid(r.id.edittext2);         final edittext e3=(edittext)findviewbyid(r.id.edittext3);         //  final arraylist<string> notelist = new arraylist<string>();         //final arrayadapter<string> aa;         b1=(button)findviewbyid(r.id.button1);         b2=(button)findviewbyid(r.id.button2);     b1.setonclicklistener(new onclicklistener() {          @override         public void onclick(view arg0) {             // todo auto-generated method stub             string s1 = e1.gettext().tostring();             string s2 = e1.gettext().tostring();             string s3 = e1.gettext().tostring();              bundle b=new bundle();             b.putstringarray("key", new string[]{s1, s2,s3});             intent i=new intent(getapplicationcontext(), secondactivity.class);             i.putextras(b);             startactivity(i);          }     });     b2.setonclicklistener(new onclicklistener() {          @override         public void onclick(view v) {             // todo auto-generated method stub         intent = new intent(mainactivity.this,secondactivity.class);         startactivity(i);         }     });     }  } 

secondactivity.java

   package com.example.listdemo;  import android.os.bundle; import android.app.activity; import android.app.listactivity; import android.content.intent; import android.sax.startelementlistener; import android.view.menu; import android.view.view; import android.view.view.onclicklistener; import android.widget.arrayadapter; import android.widget.button; import android.widget.listview; import android.widget.toast;  public class secondactivity extends activity {     listview ls;     button bt;         @override         protected void oncreate(bundle savedinstancestate) {             super.oncreate(savedinstancestate);             setcontentview(r.layout.activity_second);                ls=(listview)findviewbyid(r.id.list1);                bundle b=this.getintent().getextras();               string[] array=b.getstringarray("key");                ls.setadapter(new arrayadapter(this, android.r.layout.simple_list_item_1,array));                bt.setonclicklistener(new onclicklistener() {                  @override                 public void onclick(view arg0) {                     // todo auto-generated method stub                 intent =new intent(secondactivity.this,mainactivity.class);                 startactivity(i);                 }             });         }      } 

seconactivity.xml

<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"     android:layout_width="fill_parent"     android:layout_height="fill_parent"     android:orientation="vertical" >      <listview         android:id="@+id/list1"         android:layout_width="match_parent"         android:layout_height="306dp" >     </listview>      <button         android:id="@+id/button1"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:text="back"         android:layout_margintop="20dp"         android:layout_gravity="center" />  </linearlayout> 

logcat

05-10 15:41:50.279: w/keycharactermap(3629): no keyboard id 0 05-10 15:41:50.279: w/keycharactermap(3629): using default keymap: /system/usr/keychars/qwerty.kcm.bin 05-10 15:41:58.657: d/androidruntime(3629): shutting down vm 05-10 15:41:58.667: w/dalvikvm(3629): threadid=1: thread exiting uncaught exception (group=0x40015560) 05-10 15:41:58.688: e/androidruntime(3629): fatal exception: main 05-10 15:41:58.688: e/androidruntime(3629): java.lang.runtimeexception: unable start activity componentinfo{com.example.listdemo/com.example.listdemo.secondactivity}: java.lang.nullpointerexception 05-10 15:41:58.688: e/androidruntime(3629):     @ android.app.activitythread.performlaunchactivity(activitythread.java:1647) 05-10 15:41:58.688: e/androidruntime(3629):     @ android.app.activitythread.handlelaunchactivity(activitythread.java:1663) 05-10 15:41:58.688: e/androidruntime(3629):     @ android.app.activitythread.access$1500(activitythread.java:117) 05-10 15:41:58.688: e/androidruntime(3629):     @ android.app.activitythread$h.handlemessage(activitythread.java:931) 05-10 15:41:58.688: e/androidruntime(3629):     @ android.os.handler.dispatchmessage(handler.java:99) 05-10 15:41:58.688: e/androidruntime(3629):     @ android.os.looper.loop(looper.java:123) 05-10 15:41:58.688: e/androidruntime(3629):     @ android.app.activitythread.main(activitythread.java:3683) 05-10 15:41:58.688: e/androidruntime(3629):     @ java.lang.reflect.method.invokenative(native method) 05-10 15:41:58.688: e/androidruntime(3629):     @ java.lang.reflect.method.invoke(method.java:507) 05-10 15:41:58.688: e/androidruntime(3629):     @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:839) 05-10 15:41:58.688: e/androidruntime(3629):     @ com.android.internal.os.zygoteinit.main(zygoteinit.java:597) 05-10 15:41:58.688: e/androidruntime(3629):     @ dalvik.system.nativestart.main(native method) 05-10 15:41:58.688: e/androidruntime(3629): caused by: java.lang.nullpointerexception 05-10 15:41:58.688: e/androidruntime(3629):     @ com.example.listdemo.secondactivity.oncreate(secondactivity.java:33) 05-10 15:41:58.688: e/androidruntime(3629):     @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1047) 05-10 15:41:58.688: e/androidruntime(3629):     @ android.app.activitythread.performlaunchactivity(activitythread.java:1611) 05-10 15:41:58.688: e/androidruntime(3629):     ... 11 more 05-10 15:42:00.727: i/process(3629): sending signal. pid: 3629 sig: 9 

manifest.xml

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android"     package="com.example.listdemo"     android:versioncode="1"     android:versionname="1.0" >      <uses-sdk         android:minsdkversion="8"         android:targetsdkversion="17" />      <application         android:allowbackup="true"         android:icon="@drawable/ic_launcher"         android:label="@string/app_name"         android:theme="@style/apptheme" >         <activity             android:name="com.example.listdemo.mainactivity"             android:label="@string/app_name" >             <intent-filter>                 <action android:name="android.intent.action.main" />                  <category android:name="android.intent.category.launcher" />             </intent-filter>         </activity>         <activity             android:name="com.example.listdemo.secondactivity"             android:label="@string/title_activity_second" >         </activity>     </application> </manifest> 

you have not specified button id.you declared button bt.you have refernce of button specifyed in second.xml.

in error showing nullpointer exception in line 33. have written code button click. edit code , give refernce button bt below.

button bt=(button)findviewbyid(r.id.button id).

also in first activity edit this.

        string s1 = e1.gettext().tostring();         string s2 = e2.gettext().tostring();         string s3 = e3.gettext().tostring(); 

i tried code button refernce.its working fine.