Android studio 预览不显示布局 [英] Android studio preview does not show layouts
问题描述
我刚刚开始学习android studio.我遇到了一个问题:
I have just started to learn android studio. I've encountered a problem:
布局在我添加后不会出现在预览中.但是,如果我更改主题或在模拟器中运行应用程序,它们确实会出现,但会重叠.
The layouts won't appear in the preview after I have added them. But if I change the theme or run the app in the emulator they do appear but they overlap.
推荐答案
对于 API 27:
添加以下依赖:如果您使用的是 targetSdkVersion 27,在您的应用程序级别 gradle 文件 build.gradle(Module: app)
Add the following dependency: If you are using targetSdkVersion 27, in your App Level gradle file build.gradle(Module: app)
实现'com.android.support:appcompat-v7:27.1.1'
对于 API 28:
如果您使用的是 targetSdkVersion 28,
if you are using targetSdkVersion 28,
第 1 步:确保您有以下依赖项:
实现'com.android.support:appcompat-v7:28.0.0-rc02'
更新:有关最新的 appcompat-v7 库存储库版本,请点击此链接
UPDATE: For the latest appcompat-v7 library repo version, follow this link
https://mvnrepository.com/artifact/com.android.support/appcompat-v7?repo=google
第 2 步:
转到值>styles.xml 并修改样式如下,
Goto Values > styles.xml and modify the style as follows,
<style name="AppTheme" parent="Base.Theme.AppCompat.Light.DarkActionBar">
或您喜欢的任何其他基本主题.
or any other base theme you like.
这是您的约束布局示例,
Here is an example constraint layout for you,
<?xml version="1.0" encoding="utf-8"?>
<android.support.constraint.ConstraintLayout
xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
xmlns:app="http://schemas.android.com/apk/res-auto">
<EditText
android:id="@+id/enter_age"
android:layout_width="200dp"
android:layout_height="100dp"
android:ems="10"
android:hint="enter age"
android:inputType="number"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:layout_constraintBottom_toTopOf="@+id/button1"
app:layout_constraintVertical_chainStyle="packed" />
<Button
android:id="@+id/button1"
android:layout_width="200dp"
android:layout_height="110dp"
android:onClick="butGetAge"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintTop_toBottomOf="@id/enter_age"
app:layout_constraintBottom_toBottomOf="parent"/>
</android.support.constraint.ConstraintLayout>
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