android - Crash when clicking button with custom theme -

i creating custom theme button , using android:onclick event of button xml handle click of button.

due reason crashing below exception

java.lang.illegalstateexception: not find method myonclick(view) in activity class android.view.contextthemewrapper onclick handler on view class android.widget.button id 'button1'

and working fine if remove theme attribute button, below theme button

    <style name="buttontheme" parent="@android:style/widget.button">         <item name="android:textcolor">#ff0000</item>         <item name="android:shadowcolor">#ff000000</item>     </style> 

and button defined in xml below,

    <button         android:id="@+id/button1"         android:layout_width="wrap_content"         android:layout_height="wrap_content"         android:layout_below="@+id/textview1"         android:layout_margin="20dp"         android:onclick="myonclick"         android:theme="@style/buttontheme"         android:text="button" /> 

here java code well,

public void myonclick(view view) {         switch (view.getid()) {         case r.id.button1:             getwindow().setstatusbarcolor(getresources()                                    .getcolor(r.color.statusbarcolor));             getwindow().setnavigationbarcolor(getresources()                                    .getcolor(r.color.statusbarcolor));             break;          default:             break;         }      } 

so, reason crashing? able handle click event if remove android:theme="@style/buttontheme" attribute button widget xml.

i've never seen applying android:theme attribute individual view, after bit of googling found out indeed possible, since android 5.0.

a hint of can seen @ end here.

and more detail here.

as second link explains, contextthemewrapper used modify theme associated base context. however, since activity need hold on own theme, can imagine new contextthemewrapper created , assigned new context of view. since new context not activity more, callback functions don't exist here , error describe.

you can use debugger prove (i used android studio, can use ide of choice, details might different).

1. run app in debug mode theme attribute set.
2. when exception, stacktrace contain reference view class invokes onclick.
3. use add breakpoint before exception occurs.
4. now run app again in debug mode, click button
5. when hit breakpoint evaluate expression getcontext(). see returns object of type contextthemewrapper , have member mbase points actual activity, getcontext() not return activity , not have callback functions defined on activity.
6. now remove theme attribute, leave breakpoint , run app again.
7. when hit breakpoint, evaluate expression getcontext() again , see time returns activity directly, why callbacks work, if don't set theme attribute.

in short, seems can't use android:onclick attribute if want make use of new feature, , have manually assign onclicklistener described here