android - FindViewById returns null on custom relative layout -

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in init method, findviewbyid returns null on r.id.disable_view_content. 

public class disableview extends relativelayout {      private view content;     private view disableview;     private int disablebackgroundcolor;     private boolean isenabled;      public disableview(context context) {         super(context);         init();     }      public disableview(context context, attributeset attrs) {         super(context, attrs);         obtainattributes(context, attrs);         init();     }      public disableview(context context, attributeset attrs, int defstyleattr) {         super(context, attrs, defstyleattr);         obtainattributes(context, attrs);         init();     }      @targetapi(build.version_codes.lollipop)     public disableview(context context, attributeset attrs, int defstyleattr, int defstyleres) {         super(context, attrs, defstyleattr, defstyleres);         obtainattributes(context, attrs);         init();     }      private void obtainattributes(context context, attributeset attributeset) {         typedarray typedarray = context.gettheme().obtainstyledattributes(attributeset, r.styleable.disableview, 0, 0);         disablebackgroundcolor = typedarray.getcolor(r.styleable.disableview_disablebackground, 0x00000000);         isenabled = typedarray.getboolean(r.styleable.disableview_enabled, false);         typedarray.recycle();     }      private void init() {         content = findviewbyid(r.id.disable_view_content);         disableview = new view(getcontext());         relativelayout.layoutparams lp = new layoutparams(viewgroup.layoutparams.match_parent, viewgroup.layoutparams.match_parent);         lp.addrule(relativelayout.align_top, r.id.disable_view_content);         lp.addrule(relativelayout.align_bottom, r.id.disable_view_content);         lp.addrule(relativelayout.align_left, r.id.disable_view_content);         lp.addrule(relativelayout.align_top, r.id.disable_view_content);         disableview.setbackgroundresource(disablebackgroundcolor);         disableview.setlayoutparams(lp);         setenabled(isenabled);     }      public void setenabled(boolean enabled) {         content.setenabled(enabled);         if(enabled) disableview.setvisibility(view.gone);         else disableview.setvisibility(view.visible);     } }

here's xml

<com....view.common.disableview         android:id="@+id/..._disableview_...disable"         android:layout_width="match_parent"         android:layout_height="wrap_content">         <linearlayout             android:id="@id/disable_view_content"             android:layout_width="match_parent"             android:layout_height="wrap_content">             <textview                 android:id="@+id/..._textview_..."                 android:layout_width="match_parent"                 android:layout_height="wrap_content"                 android:background="@drawable/shape_rect_green"                 android:gravity="center"                 android:paddingtop="18dp"                 android:paddingbottom="18dp"                 android:layout_marginbottom="12dp"                 android:textsize="@dimen/size_text"                 android:text="@string/..."                 android:textcolor="@android:color/white"                 android:duplicateparentstate="true"/>         </linearlayout>     </com....view.common.disableview>

id disable_view_content in attr.xml

<resources>     <item type="id" name="disable_view_content"/> </resources>

everything seems fine, view id disable_view_content direct child of disableview. either in edit mode or on app, null pointer because reference content null.

edit: here's stack trace:

 caused by: java.lang.nullpointerexception: attempt invoke virtual method 'void android.view.view.setenabled(boolean)' on null object reference             @ com....view.common.disableview.setenabled(disableview.java:71)             @ com....view.common.disableview.init(disableview.java:67)             @ com....view.common.disableview.<init>(disableview.java:35)

you calling findviewbyid() far in view's lifecycle.

your init() called directly constructor, , before have created layout own view. @ point in time, view has no layout , has no children either.

the earliest can access child views after 1 of addview() methods has been called.


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