Switch Android Studio3.5.2 default layout ConstraintLayout to LinearLayout

1. Find the path to install Android Studio 3.5.2

Android Studio\\plugins\\android\\lib\\templates\\activities\\common\\root\\res\\layout

2. Open the simple.xml.ftl file with Notepad, the content is as follows:

<?xml version="1.0" encoding="utf-8"?>
<${getMaterialComponentName('android.support.constraint.ConstraintLayout', useAndroidX)}
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
<#if appBarLayoutName??>
    app:layout_behavior="@string/appbar_scrolling_view_behavior"
    tools:showIn="@layout/${appBarLayoutName}"
</#if>
    tools:context="${packageName}.${activityClass}">

<#if isNewProject!false>
    <TextView
<#if includeCppSupport!false>
        android:id="@+id/sample_text"
</#if>
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

</#if>
</${getMaterialComponentName('android.support.constraint.ConstraintLayout', useAndroidX)}>

3. Delete all the codes in the simple.xml.ftl file and replace them with the following codes:

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical">

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World!" />
</LinearLayout>

4. Restart Android Studio 3.5.2.