文件预览：activity_main.xml

<?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="match_parent"> <androidx.appcompat.widget.Toolbar android:layout_width="match_parent" android:layout_height="wrap_content" android:id="@+id/activitymainToolbar1"/> <LinearLayout xmlns:app="http://schemas.android.com/apk/res-auto" android:orientation="vertical" android:layout_width="match_parent" android:layout_height="0dp" android:gravity="center" android:layout_weight="1.0"> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Hello, WinBoll!"/> </LinearLayout> </LinearLayout>