按钮在LinearLayout中不显示

Question

我使用LinearLayout来显示一个简单的标题、正文以及保存和取消按钮。但是我看不到Save按钮。缺少了什么?

<?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"
tools:context=".SecondFragment">
<TextView
android:id="@+id/tv_title"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="@string/title"
android:layout_margin="12dp" />
<EditText
android:id="@+id/et_title"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/edit_title"
android:layout_margin="12dp"
/>
<EditText
android:id="@+id/et_body"
android:background="@drawable/edit_text_border"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:textColor="@android:color/darker_gray"
android:text="Lorem ipsum dolor sit amet, consectetur adipiscing elit. Praesent nec est consequat arcu laoreet consequat non eget quam. Mauris ullamcorper odio id erat pharetra, sed auctor libero tempor. Sed sit amet justo facilisis nisl pharetra mollis. Donec vel felis eget dolor tristique consectetur at nec tortor. Donec eu finibus leo. Fusce non erat semper turpis tincidunt volutpat sit amet sit amet elit."
android:justificationMode="inter_word"/>
<Button
android:id="@+id/button_save"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:layout_marginTop="16dp"
android:text="@string/save"
android:textAllCaps="false"
style="?android:attr/buttonBarButtonStyle" />
<Button
android:id="@+id/button_cancel"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="@string/cancel"
android:textAllCaps="false"
style="?android:attr/buttonBarButtonStyle" />
</LinearLayout>

Answer 1

显然在布局文件夹中有另一个fragment_second.xml作为v26，删除后，它像一个魅力一样工作!