The true meaning and testing of "Android" View.getrootview ()

The official explanation for View.getrootview () is: Finds the topmost view in the current view hierarchy. find the top-most view in the current view hierarchy

My understanding is to find the root view of the view hierarchy where the view instance resides.

To confirm the true meaning of this view.getrootview (), I tested the following:

Activity_main.xml:

<absolutelayout xmlns:android= "http://schemas.android.com/apk/res/android"    android:layout_width= "Match_ Parent "    android:layout_height=" match_parent ">  <include       layout=" @layout/test_layout "/>< /absolutelayout>

Test_layout.xml:

<?xml version= "1.0" encoding= "Utf-8"? ><linearlayout xmlns:android= "http://schemas.android.com/apk/res/ Android "    android:layout_width=" match_parent "    android:layout_height=" match_parent "    android:o rientation= "vertical" >    <relativelayout         android:layout_width= "wrap_content"        android:layout_ height= "Wrap_content" >        <button                android:id= "@+id/testbtn"   android:layout_width= "Match_parent"   android:layout_height= "wrap_content"/>    </RelativeLayout></LinearLayout>

Mainactivity.java:

public class Mainactivity extends Activity {@Overrideprotected void onCreate (Bundle savedinstancestate) {super.oncreate (savedinstancestate); Setcontentview (R.layout.activity_main); Button testbtn = (button) Findviewbyid (R.ID.TESTBTN); LOG.I ("Testbtn", testbtn.tostring () + "ID:" +testbtn.getid ()); LOG.I ("Testbtn ' s Rootview", Testbtn.getrootview (). toString () + "ID:" +testbtn.getrootview (). GetId ()); View TestView =layoutinflater.from (this). Inflate (r.layout.test_layout, NULL); Button testBtn2 = (button) Testview.findviewbyid (R.ID.TESTBTN); LOG.I ("TestBtn2", testbtn2.tostring () + "ID:" +testbtn2.getid ()); LOG.I ("TestBtn2 ' s Rootview", Testbtn2.getrootview (). toString () + "ID:" +testbtn2.getrootview (). GetId ()); View Decorview = GetWindow (). Getdecorview (); View Contentview =decorview.findviewbyid (android. R.id.content); View Mainrootview = ((ViewGroup) contentview). Getchildat (0); LOG.I ("Decorview", decorview.tostring () + "ID:" +decorview.getid ()); LOG.I ("Contentview", contentview.tostring () + "ID:" +contentview.getid()); LOG.I ("Mainrootview", mainrootview.tostring () + "ID:" +mainrootview.getid ());}}

Printing results:

from the printed results we need to note that testbtn, testBtn2 although the same ID, but it is a different instance, they are located in the same view hierarchy, so they get through the Getrootview root view is not the same.

Finally, we can see that to get the root view of the XML file used by the current interface, you can use the

View Rootview = ((ViewGroup) (GetWindow (). Getdecorview (). Findviewbyid (Android. r.id.content)). Getchildat (0);

To get.

The true meaning and testing of "Android" View.getrootview ()