“center_horizo​​ntal 与属性重力不兼容....” xml 新手，我不明白我的问题是什么

Question

I am trying to make an app that has two buttons side by side, and a number above those buttons (with that whole arrangement being centered vertically on the screen). The end goal is to eventually be able to have multiples of those but for now I just want to get at least one right. Anyway, for some reason I keep getting "failed linking file resources" as well as the error in the title. My code is below

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:gravity="center_horizontal">


<TextView
    android:text="0"
    android:textSize="100sp"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/text_view1" />

<LinearLayout 
    android:orientation="horizontal"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:gravity="center_horiztonal">


        <Button
            android:text="+"
            android:textSize="75sp"
            android:gravity="center"
            android:layout_width="fill_parent"
            android:layout_height="200px"
            android:layout_weight="0.5"
            android:id="@+id/button1" />

        <Button
            android:text="-"
            android:textSize="75sp"
            android:gravity="center"
            android:layout_width="fill_parent"
            android:layout_height="200px"
            android:layout_weight="0.5"
            android:id="@+id/button2" />


</LinearLayout>

Answer 1

Do you want to achieve the result like following screenshot.

Please add following code, you should add </LinearLayout> in the end, and set the android:orientation="vertical" for the first LinearLayout

<?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"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent" 
    android:orientation="vertical"
    android:gravity="center_horizontal"
    >

<TextView
    android:text="0"
    android:textSize="100sp"
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/text_view1" />

<LinearLayout 
    android:orientation="horizontal"
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:gravity="center_horiztonal">


        <Button
            android:text="+"
            android:textSize="75sp"
            android:gravity="center"
            android:layout_width="fill_parent"
            android:layout_height="200px"
            android:layout_weight="0.5"
            android:id="@+id/button1" />

        <Button
            android:text="-"
            android:textSize="75sp"
            android:gravity="center"
            android:layout_width="fill_parent"
            android:layout_height="200px"
            android:layout_weight="0.5"
            android:id="@+id/button2" />


</LinearLayout>

</LinearLayout>