Android Shared Element Animation doesn't work for me -

i following instruction on https://developer.android.com/training/material/animations.html , trying implement animation shared element between activities, doesn't work me, searched lot not find answer, there can take look? thank much!

my steps:

1, create directory "transition" under "res" directory, , create file list_to_details.xml there:

<?xml version="1.0" encoding="utf-8"?> <transitionset xmlns:android="http://schemas.android.com/apk/res/android">     <changeimagetransform/> </transitionset> 

2, create directory "values-v21" under "res" directory, , create file styles.xml there(setting transition defined above in step 1):

<?xml version="1.0" encoding="utf-8"?> <resources>     <style name="apptheme" parent="android:theme.material">         <!-- enable window content transitions -->         <item name="android:windowcontenttransitions">true</item>          <!-- specify enter , exit transitions -->         <item name="android:windowsharedelemententertransition">@transition/list_to_detail</item>         <item name="android:windowsharedelementexittransition">@transition/list_to_detail</item>     </style> </resources> 

3, set application theme "apptheme" defined in new styles file

<application         android:name="com.myapp.myapplication"         android:allowbackup="false"         android:icon="@drawable/icon"         android:label="@string/app_name"         android:theme="@style/apptheme" > 

4, add transitionname shared element in activity , b: a: b:

5, add code start activity b in activity a:

expandedimageview.setonclicklistener(new view.onclicklistener() {   @override   public void onclick(view v) {     activityoptions options = activityoptions.makescenetransitionanimation(detaildemoactivity.this, v, "todetail");     intent intent = new intent(detaildemoactivity.this, anotherdetaildemoactivity.class);     intent.putextra("original_url", originalurl);     activitycompat.startactivity(detaildemoactivity.this, intent, options.tobundle());   } }); 

6, try app doesn't play animation, guessing reason might have async task in activity b load image, still doesn't work after tried postponeentertransition, tried getsharedelemententertransition, debugger showed null, see code:

@override protected void oncreate(bundle savedinstancestate) {   postponeentertransition();    intent intent = this.getintent();   originalurl = intent.getstringextra("original_url");    getbigimageasynctask  getbigimagetask = new getbigimageasynctask();   getbigimagetask.execute();    super.oncreate(savedinstancestate);   setcontentview(r.layout.another_detail_demo);   // have tried settransitionname() here doesn't work }  private void schedulestartpostponedtransition(final view sharedelement) {   sharedelement.getviewtreeobserver().addonpredrawlistener(       new viewtreeobserver.onpredrawlistener() {         @override         public boolean onpredraw() {           sharedelement.getviewtreeobserver().removeonpredrawlistener(this);           startpostponedentertransition();           return true;         }       }); }  private class getbigimageasynctask extends asynctask<object, void, bitmap> {   @override   protected bitmap doinbackground(object... urls) {     inputstream input = null;     httpurlconnection connection = null;     try {       url url = new url(originalurl);       connection = (httpurlconnection) url.openconnection();       connection.setdoinput(true);       connection.connect();       input = connection.getinputstream();       bitmap mybitmap = bitmapfactory.decodestream(input);       return mybitmap;     } catch (exception e) {       return null;     } {       if (connection != null) {         connection.disconnect();       }        if (input != null) {         try {           input.close();         } catch (exception e) {          }       }     }   }    @override   protected void onpostexecute(bitmap result) {     imageview expandedimageview =         (imageview) findviewbyid(r.id.another_demo_expanded_image);     expandedimageview.setimagedrawable(new bitmapdrawable(result));     schedulestartpostponedtransition(expandedimageview);      final transition transition = anotherdetaildemoactivity.this.getwindow().getsharedelemententertransition();      // in fact here object transition null      if (transition != null) {       // there entering shared element transition add listener       transition.addlistener(new transition.transitionlistener() {         @override         public void ontransitionend(transition transition) {           transition.removelistener(this);         }          @override         public void ontransitionstart(transition transition) {         }          @override         public void ontransitioncancel(transition transition) {           // make sure remove ourselves listener           transition.removelistener(this);         }          @override         public void ontransitionpause(transition transition) {           // no-op         }          @override         public void ontransitionresume(transition transition) {           // no-op         }       });     }   } } 

is there wrong or missed in steps? highly appreciated!

just made work.

two problems affect:

1. i need use java code change instead of xml changes(not sure why, guess maybe there's wrong in android sdk parse xml changes)
2. i need add window.requestfeature(window.feature_activity_transitions) make work, feature not mentioned in android developer site, mentioned in stakeoverflow question.