App Crashing using Android Studio, Sunshine App, cant get the concept of AsynTask -

i m particularly new in programming, , not getting figure out error, whenever run it, either on emulator or on mobile, says, app has stopped working. please me figure out thanx in advance

main activity

package com.example.android.sunshine.app;  import android.annotation.targetapi; import android.support.v4.app.fragment; import android.os.build; import android.os.bundle; import android.support.v7.app.appcompatactivity; import android.util.log; import android.view.layoutinflater; import android.view.menu; import android.view.menuitem; import android.view.view; import android.view.viewgroup; import android.widget.arrayadapter; import android.widget.listview; import android.widget.textview;  import java.io.bufferedreader; import java.io.ioexception; import java.io.inputstream; import java.io.inputstreamreader; import java.net.httpurlconnection; import java.net.url; import java.util.arraylist; import java.util.arrays;     import java.util.list;      public class mainactivity extends appcompatactivity {      @override     protected void oncreate(bundle savedinstancestate) {         super.oncreate(savedinstancestate);         setcontentview(r.layout.activity_main);         if (savedinstancestate == null){          getsupportfragmentmanager().begintransaction()          .add(r.id.container, new forecastfragment())          .commit();           }     }       @override     public boolean oncreateoptionsmenu(menu menu) {         // inflate menu; adds items action bar if present.         getmenuinflater().inflate(r.menu.main, menu);         return true;     }      @override     public boolean onoptionsitemselected(menuitem item) {         // handle action bar item clicks here. action bar         // automatically handle clicks on home/up button, long         // specify parent activity in androidmanifest.xml.         int id = item.getitemid();          //noinspection simplifiableifstatement         if (id == r.id.action_settings) {             return true;         }          return super.onoptionsitemselected(item);     } } 

forecastfragement

package com.example.android.sunshine.app;  import android.os.asynctask; import android.os.bundle; import android.support.v4.app.fragment; import android.util.log; import android.view.layoutinflater; import android.view.view; import android.view.viewgroup; import android.widget.arrayadapter; import android.widget.listview;  import java.io.bufferedreader; import java.io.ioexception; import java.io.inputstream; import java.io.inputstreamreader; import java.net.httpurlconnection; import java.net.url; import java.util.arraylist; import java.util.arrays; import java.util.list;  /**  * created nabahat on 7/8/2015.  */ public class forecastfragment extends fragment {      public forecastfragment(){}      @override     public view oncreateview(layoutinflater inflater, viewgroup container,                              bundle savedinstancestate) {         view rootview = inflater.inflate(r.layout.fragment_main, container, false);         string[] forecastarray = {                 "today - sunny - 88/63",                 "tomorrow - foggy - 70/40",                 "weds - cloudy - 72/63",                 "thurs - asteroids - 75/65",                 "fri - heavy rain - 65/56",                 "sat - trapped in weatherstation - 60/51",                 "sun - sunny - 80/68"         };          list<string> weekforecast = new arraylist<string>(                 arrays.aslist(forecastarray));          arrayadapter<string> mforecastadapter = new arrayadapter<string>(                 getactivity(),                 r.layout.list_item_forecast,                 r.id.list_item_forecast_textview,                 weekforecast);         listview listview = (listview) rootview.findviewbyid(r.id.listview_forecast);         listview.setadapter(mforecastadapter);          return rootview;     }      public class fetchweathertask extends asynctask<void, void, void> {         private final string log_tag = fetchweathertask.class.getsimplename();          @override         protected void doinbackground(void... params){             httpurlconnection urlconnection = null;             bufferedreader reader = null;             string forecastjsonstr = null;              try {                 url url = new url("http://api.openweathermap.org/data/2.5/forecast/daily?q=94043&mode=json&units=metric&cnt=7");                 urlconnection = (httpurlconnection) url.openconnection();                 urlconnection.setrequestmethod("get");                 urlconnection.connect();                  inputstream inputstream = urlconnection.getinputstream();                 stringbuffer buffer = new stringbuffer();                 if (inputstream == null) {                     return null;                 }                 reader = new bufferedreader(new inputstreamreader(inputstream));                  string line;                 while ((line = reader.readline()) != null) {                     buffer.append(line + "\n");                 }                  if (buffer.length() == 0) {                     return null;                 }                 forecastjsonstr = buffer.tostring();             } catch (ioexception e) {                 log.e(log_tag, "error ", e);                 return null;              } finally{                 if (urlconnection != null) {                     urlconnection.disconnect();                 }                 if (reader != null) {                     try {                         reader.close();                     } catch (final ioexception e) {                         log.e(log_tag, "error closing stream", e);                     }                 }             }         return null;         }     } } 

activity_main.xml

<fragment xmlns:android="http://schemas.android.com/apk/res/android"     xmlns:tools="http://schemas.android.com/tools"     android:id="@+id/fragment"     android:name="com.example.android.sunshine.app.mainactivity"     tools:layout="@layout/fragment_main"     android:layout_width="match_parent"     android:layout_height="match_parent" /> 

androidmanifest

<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android"     package="com.example.android.sunshine.app" >      <application         android:allowbackup="true"         android:icon="@mipmap/ic_launcher"         android:label="@string/app_name"         android:theme="@style/apptheme" >         <activity             android:name=".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>     </application>  </manifest> 

fragment_main.xml

<framelayout     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="64dp"     android:paddingright="64dp"     android:paddingtop="@dimen/activity_vertical_margin"     android:paddingbottom="@dimen/activity_vertical_margin"     tools:context="com.example.sunshine.app.mainactivityfragment$placeholderfragment"     android:id="@+id/container">      <listview         android:id="@+id/listview_forecast"         android:layout_width="match_parent"         android:layout_height="match_parent" />  </framelayout> 

here log

02-04 07:12:41.022  11478-11478/? e/libegl﹕ call opengl es api no current context (logged once per thread) 02-04 07:17:25.447  12449-12449/? e/trace﹕ error opening trace file: no such file or directory (2) 02-04 07:17:27.697  12474-12474/? e/trace﹕ error opening trace file: no such file or directory (2) 02-04 07:17:28.202  12492-12492/? e/trace﹕ error opening trace file: no such file or directory (2) 02-04 07:17:28.313  12506-12506/? e/trace﹕ error opening trace file: no such file or directory (2) 02-04 07:17:28.457  12524-12524/? e/trace﹕ error opening trace file: no such file or directory (2) 02-04 07:17:28.706  12547-12547/? e/trace﹕ error opening trace file: no such file or directory (2) 02-04 07:17:28.802  12547-12553/? e/jdwp﹕ failed sending reply debugger: broken pipe 02-04 07:17:28.853  12547-12547/? e/androidruntime﹕ fatal exception: main     java.lang.runtimeexception: unable start activity componentinfo{com.example.android.sunshine.app/com.example.android.sunshine.app.mainactivity}: android.view.inflateexception: binary xml file line #2: error inflating class fragment             @ android.app.activitythread.performlaunchactivity(activitythread.java:2351)             @ android.app.activitythread.handlelaunchactivity(activitythread.java:2403)             @ android.app.activitythread.access$600(activitythread.java:165)             @ android.app.activitythread$h.handlemessage(activitythread.java:1373)             @ android.os.handler.dispatchmessage(handler.java:107)             @ android.os.looper.loop(looper.java:194)             @ android.app.activitythread.main(activitythread.java:5370)             @ java.lang.reflect.method.invokenative(native method)             @ java.lang.reflect.method.invoke(method.java:525)             @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:833)             @ com.android.internal.os.zygoteinit.main(zygoteinit.java:600)             @ dalvik.system.nativestart.main(native method)      caused by: android.view.inflateexception: binary xml file line #2: error inflating class fragment             @ android.view.layoutinflater.createviewfromtag(layoutinflater.java:704)             @ android.view.layoutinflater.inflate(layoutinflater.java:466)             @ android.view.layoutinflater.inflate(layoutinflater.java:396)             @ android.view.layoutinflater.inflate(layoutinflater.java:352)             @ android.support.v7.app.appcompatdelegateimplv7.setcontentview(appcompatdelegateimplv7.java:249)             @ android.support.v7.app.appcompatactivity.setcontentview(appcompatactivity.java:106)             @ com.example.android.sunshine.app.mainactivity.oncreate(mainactivity.java:34)             @ android.app.activity.performcreate(activity.java:5122)             @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1146)             @ android.app.activitythread.performlaunchactivity(activitythread.java:2315)             at android.app.activitythread.handlelaunchactivity(activitythread.java:2403)             at android.app.activitythread.access$600(activitythread.java:165)             at android.app.activitythread$h.handlemessage(activitythread.java:1373)             at android.os.handler.dispatchmessage(handler.java:107)             at android.os.looper.loop(looper.java:194)             at android.app.activitythread.main(activitythread.java:5370)             at java.lang.reflect.method.invokenative(native method)             at java.lang.reflect.method.invoke(method.java:525)             at com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:833)             at com.android.internal.os.zygoteinit.main(zygoteinit.java:600)             at dalvik.system.nativestart.main(native method)      caused by: java.lang.classcastexception: com.example.android.sunshine.app.mainactivity cannot cast android.app.fragment             @ android.app.fragment.instantiate(fragment.java:585)             @ android.app.fragment.instantiate(fragment.java:560)             @ android.app.activity.oncreateview(activity.java:4727)             @ android.support.v7.app.appcompatdelegateimplv11.callactivityoncreateview(appcompatdelegateimplv11.java:41)             @ android.support.v7.app.appcompatdelegateimplv7.oncreateview(appcompatdelegateimplv7.java:826)             @ android.support.v4.view.layoutinflatercompathc$factorywrapperhc.oncreateview(layoutinflatercompathc.java:44)             @ android.view.layoutinflater.createviewfromtag(layoutinflater.java:675)             at android.view.layoutinflater.inflate(layoutinflater.java:466)             at android.view.layoutinflater.inflate(layoutinflater.java:396)             at android.view.layoutinflater.inflate(layoutinflater.java:352)             at android.support.v7.app.appcompatdelegateimplv7.setcontentview(appcompatdelegateimplv7.java:249)             at android.support.v7.app.appcompatactivity.setcontentview(appcompatactivity.java:106)             at com.example.android.sunshine.app.mainactivity.oncreate(mainactivity.java:34)             at android.app.activity.performcreate(activity.java:5122)             at android.app.instrumentation.callactivityoncreate(instrumentation.java:1146)             at android.app.activitythread.performlaunchactivity(activitythread.java:2315)             at android.app.activitythread.handlelaunchactivity(activitythread.java:2403)             at android.app.activitythread.access$600(activitythread.java:165)             at android.app.activitythread$h.handlemessage(activitythread.java:1373)             at android.os.handler.dispatchmessage(handler.java:107)             at android.os.looper.loop(looper.java:194)             at android.app.activitythread.main(activitythread.java:5370)             at java.lang.reflect.method.invokenative(native method)             at java.lang.reflect.method.invoke(method.java:525)             at com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:833)             at com.android.internal.os.zygoteinit.main(zygoteinit.java:600)             at dalvik.system.nativestart.main(native method) 02-04 07:17:29.027  12563-12563/? e/trace﹕ error opening trace file: no such file or directory (2) 02-04 07:17:29.361  12580-12580/? e/trace﹕ error opening trace file: no such file or directory (2) 02-04 07:17:29.550  12599-12599/? e/trace﹕ error opening trace file: no such file or directory (2) 02-04 07:17:29.609  12612-12612/? e/trace﹕ error opening trace file: no such file or directory (2) 02-04 07:17:32.472  12639-12639/? e/trace﹕ error opening trace file: no such file or directory (2) 02-04 07:17:34.982      493-511/? e/keyguardupdatemonitor﹕ object tried add callback     java.lang.exception: called             @ com.android.internal.policy.impl.keyguard.keyguardupdatemonitor.registercallback(keyguardupdatemonitor.java:1108)             @ com.android.internal.policy.impl.keyguard.keyguardselectorview.onresume(keyguardselectorview.java:331)             @ com.android.internal.policy.impl.keyguard.keyguardhostview.onscreenturnedon(keyguardhostview.java:1118)             @ com.android.internal.policy.impl.keyguard.keyguardviewmanager.onscreenturnedon(keyguardviewmanager.java:403)             @ com.android.internal.policy.impl.keyguard.keyguardviewmediator.handlenotifyscreenon(keyguardviewmediator.java:1813)             @ com.android.internal.policy.impl.keyguard.keyguardviewmediator.access$2400(keyguardviewmediator.java:106)             @ com.android.internal.policy.impl.keyguard.keyguardviewmediator$4.handlemessage(keyguardviewmediator.java:1449)             @ android.os.handler.dispatchmessage(handler.java:107)             @ android.os.looper.loop(looper.java:194)             @ android.os.handlerthread.run(handlerthread.java:60) 02-04 07:17:35.083     120-1870/? e/audiomtkhardware﹕ setcommonparameters() still have param.size() = 1, remain param = "screen_state=on" 02-04 07:17:41.110  12672-12672/com.example.android.sunshine.app e/trace﹕ error opening trace file: no such file or directory (2) 02-04 07:17:41.247  12672-12672/com.example.android.sunshine.app e/androidruntime﹕ fatal exception: main     java.lang.runtimeexception: unable start activity componentinfo{com.example.android.sunshine.app/com.example.android.sunshine.app.mainactivity}: android.view.inflateexception: binary xml file line #2: error inflating class fragment             @ android.app.activitythread.performlaunchactivity(activitythread.java:2351)             @ android.app.activitythread.handlelaunchactivity(activitythread.java:2403)             @ android.app.activitythread.access$600(activitythread.java:165)             @ android.app.activitythread$h.handlemessage(activitythread.java:1373)             @ android.os.handler.dispatchmessage(handler.java:107)             @ android.os.looper.loop(looper.java:194)             @ android.app.activitythread.main(activitythread.java:5370)             @ java.lang.reflect.method.invokenative(native method)             @ java.lang.reflect.method.invoke(method.java:525)             @ com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:833)             @ com.android.internal.os.zygoteinit.main(zygoteinit.java:600)             @ dalvik.system.nativestart.main(native method)      caused by: android.view.inflateexception: binary xml file line #2: error inflating class fragment             @ android.view.layoutinflater.createviewfromtag(layoutinflater.java:704)             @ android.view.layoutinflater.inflate(layoutinflater.java:466)             @ android.view.layoutinflater.inflate(layoutinflater.java:396)             @ android.view.layoutinflater.inflate(layoutinflater.java:352)             @ android.support.v7.app.appcompatdelegateimplv7.setcontentview(appcompatdelegateimplv7.java:249)             @ android.support.v7.app.appcompatactivity.setcontentview(appcompatactivity.java:106)             @ com.example.android.sunshine.app.mainactivity.oncreate(mainactivity.java:34)             @ android.app.activity.performcreate(activity.java:5122)             @ android.app.instrumentation.callactivityoncreate(instrumentation.java:1146)             @ android.app.activitythread.performlaunchactivity(activitythread.java:2315)             at android.app.activitythread.handlelaunchactivity(activitythread.java:2403)             at android.app.activitythread.access$600(activitythread.java:165)             at android.app.activitythread$h.handlemessage(activitythread.java:1373)             at android.os.handler.dispatchmessage(handler.java:107)             at android.os.looper.loop(looper.java:194)             at android.app.activitythread.main(activitythread.java:5370)             at java.lang.reflect.method.invokenative(native method)             at java.lang.reflect.method.invoke(method.java:525)             at com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:833)             at com.android.internal.os.zygoteinit.main(zygoteinit.java:600)             at dalvik.system.nativestart.main(native method)      caused by: java.lang.classcastexception: com.example.android.sunshine.app.mainactivity cannot cast android.app.fragment             @ android.app.fragment.instantiate(fragment.java:585)             @ android.app.fragment.instantiate(fragment.java:560)             @ android.app.activity.oncreateview(activity.java:4727)             @ android.support.v7.app.appcompatdelegateimplv11.callactivityoncreateview(appcompatdelegateimplv11.java:41)             @ android.support.v7.app.appcompatdelegateimplv7.oncreateview(appcompatdelegateimplv7.java:826)             @ android.support.v4.view.layoutinflatercompathc$factorywrapperhc.oncreateview(layoutinflatercompathc.java:44)             @ android.view.layoutinflater.createviewfromtag(layoutinflater.java:675)             at android.view.layoutinflater.inflate(layoutinflater.java:466)             at android.view.layoutinflater.inflate(layoutinflater.java:396)             at android.view.layoutinflater.inflate(layoutinflater.java:352)             at android.support.v7.app.appcompatdelegateimplv7.setcontentview(appcompatdelegateimplv7.java:249)             at android.support.v7.app.appcompatactivity.setcontentview(appcompatactivity.java:106)             at com.example.android.sunshine.app.mainactivity.oncreate(mainactivity.java:34)             at android.app.activity.performcreate(activity.java:5122)             at android.app.instrumentation.callactivityoncreate(instrumentation.java:1146)             at android.app.activitythread.performlaunchactivity(activitythread.java:2315)             at android.app.activitythread.handlelaunchactivity(activitythread.java:2403)             at android.app.activitythread.access$600(activitythread.java:165)             at android.app.activitythread$h.handlemessage(activitythread.java:1373)             at android.os.handler.dispatchmessage(handler.java:107)             at android.os.looper.loop(looper.java:194)             at android.app.activitythread.main(activitythread.java:5370)             at java.lang.reflect.method.invokenative(native method)             at java.lang.reflect.method.invoke(method.java:525)             at com.android.internal.os.zygoteinit$methodandargscaller.run(zygoteinit.java:833)             at com.android.internal.os.zygoteinit.main(zygoteinit.java:600)             at dalvik.system.nativestart.main(native method) 02-04 07:17:41.285      493-513/? e/apperrordialog﹕ failed ilowstoragehandle instance 02-04 07:17:45.682      120-438/? e/﹕ audioclosedumppcmfile file== null 02-04 07:17:45.682      120-438/? e/﹕ audioclosedumppcmfile file== null 02-04 07:17:50.354      645-645/? e/wpa_supplicant﹕ sorted scan results 02-04 07:17:50.354      645-645/? e/wpa_supplicant﹕ f4:3e:61:92:4b:21 freq=2462 qual=0 noise=0 level=-83 flags=0xb 02-04 07:17:50.354      645-645/? e/wpa_supplicant﹕ ies 02-04 07:17:50.354      645-645/? e/wpa_supplicant﹕  

the issue in main activity_main.xml have used fragment tag loads required fragment, but have used wrong name of fragment. have used android:name="com.example.android.sunshine.app.mainactivity" should use android:name="com.example.android.sunshine.app.forecastfragment

since doing in xml remove transaction code written inside oncreate().

it has nothing async task