What do you mean by root view of an activity?

Question

I have a very trivial confusion regarding the what is the root view of an activity. I searched this throughout google and stack overflow. I got some knowledge about it but didn't come to a convincing solution as no one clearly said about that term. The question which seems to be alike my question tell about what a root view of a given layout is but to me they don't seem to specify the root view of an activity is.Though the answer to my question is quite intuitive, I want a definite answer with no confusion.So here is the code structure. I have the following activity class :

package com.example.android.viewpager;

import android.os.Bundle;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;


public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}

And the XML code associated with it when I created the activity is (activity_main.xml) :

    <LinearLayout 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:orientation="vertical"
    tools:context="com.example.android.viewpager.MainActivity">
    </LinearLayout>

So according to me is this activity_main.xml the root view of the MainActivity?

Answer 1

The Root View of Your MainActivity is LinearLayout

The Root View of Your Activity means the Top most parent layout of Your XML Layout

The Root View may be a RelativeLayout, CoordinatorLayout, ConstraintLayout, LinearLayout,FrameLayout

For Example

Your activity_main.xml Contain LinearLayout as parent layout than LinearLayout is your Root View which hold all the child controlls in it like Buttons, Imageview, EditText, TextView, etc....