ConstraintLayout 不能与 Android XML Preview 中的其他类一起实例化
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【中文标题】ConstraintLayout 不能与 Android XML Preview 中的其他类一起实例化【英文标题】：ConstraintLayout cannot be instantiated along with other classes in Android XML Preview 【发布时间】：2020-11-09 19:43:05 【问题描述】：有些类没有在我的 android Studio XML Preview 中呈现（它们只是显示一个带有类名的灰色矩形）。我认为我使用的库版本之间存在一些不兼容。这是我的 XML 布局。
<?xml version="1.0" encoding="utf-8"?>
<layout 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">
<data>
<variable
name="user"
type="com.mobile.githubuser.model.GithubUserProfileSummary" />
</data>
<androidx.core.widget.NestedScrollView
android:layout_
android:layout_
android:fillViewport="true">
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_
android:layout_
android:orientation="vertical">
<com.google.android.material.appbar.MaterialToolbar
android:id="@+id/act_details_toolbar"
android:layout_
android:layout_
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"
app:title="@string/act_user_details_toolbar_title" />
<com.google.android.material.imageview.ShapeableImageView
style="@style/Widget.GithubUser.ShapeableImageView.Circular"
android:id="@+id/shapeableImageView"
android:layout_
android:layout_
android:layout_marginTop="@dimen/keyline_5"
android:src="@user.avatar"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/act_details_toolbar" />
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView"
android:layout_
android:layout_
android:layout_marginStart="@dimen/keyline_4"
android:layout_marginTop="@dimen/keyline_4"
android:layout_marginEnd="@dimen/keyline_4"
android:text="@user.name"
android:textAlignment="center"
android:textAppearance="?attr/textAppearanceHeadline2"
android:textColor="?attr/colorOnBackground"
app:layout_constraintTop_toBottomOf="@+id/shapeableImageView"
tools:layout_editor_absoluteX="16dp"
tools:text="april_ludgate" />
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView2"
android:layout_
android:layout_
android:layout_marginStart="@dimen/keyline_4"
android:layout_marginTop="@dimen/keyline_2"
android:layout_marginEnd="@dimen/keyline_4"
android:text="@`@` + user.username"
android:textAlignment="center"
android:textAppearance="?attr/textAppearanceSubtitle2"
android:textColor="?attr/colorOnBackground"
android:textSize="16sp"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/materialTextView"
tools:text="April Ludgate" />
<include
android:id="@+id/act_details_details"
layout="@layout/include_user_details"
android:layout_
android:layout_
android:layout_marginStart="@dimen/keyline_4"
android:layout_marginTop="@dimen/keyline_5"
android:layout_marginEnd="@dimen/keyline_4"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/materialTextView2" />
<com.google.android.material.tabs.TabLayout
android:id="@+id/act_details_tab_layout"
android:layout_
android:layout_
android:layout_marginTop="@dimen/keyline_5"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@id/act_details_details" />
<androidx.viewpager2.widget.ViewPager2
android:id="@+id/act_details_pager"
android:layout_
android:layout_
android:clipChildren="false"
android:clipToPadding="false"
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/act_details_tab_layout" />
</androidx.constraintlayout.widget.ConstraintLayout>
</androidx.core.widget.NestedScrollView>
</layout>
我在那里添加了另一个布局。这是我包含的布局文件 XML。
<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout 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_
android:layout_
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/materialTextView2">
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView3"
android:layout_
android:layout_
android:drawableStart="@drawable/drawable_company"
android:drawablePadding="@dimen/keyline_2"
android:text="@string/company_label"
android:textAlignment="center"
android:textAppearance="?attr/textAppearanceBody1"
android:textColor="?attr/colorOnBackground"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent" />
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView4"
android:layout_
android:layout_
android:layout_marginTop="@dimen/keyline_0"
android:drawableStart="@drawable/drawable_location"
android:drawablePadding="@dimen/keyline_2"
android:text="@string/location_label"
android:textAlignment="center"
android:textAppearance="?attr/textAppearanceBody1"
android:textColor="?attr/colorOnBackground"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/materialTextView3" />
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView5"
android:layout_
android:layout_
android:layout_marginTop="@dimen/keyline_0"
android:drawableStart="@drawable/drawable_repository"
android:drawablePadding="@dimen/keyline_2"
android:text="@string/repository_label"
android:textAlignment="center"
android:textAppearance="?attr/textAppearanceBody1"
android:textColor="?attr/colorOnBackground"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/materialTextView4" />
<androidx.constraintlayout.widget.Barrier
android:id="@+id/barrier2"
android:layout_
android:layout_
app:barrierDirection="right"
app:constraint_referenced_ids="materialTextView3,materialTextView4,materialTextView5" />
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView8"
android:layout_
android:layout_
android:layout_marginStart="@dimen/keyline_2"
android:text="@`: ` + user.organizations"
android:textAppearance="?attr/textAppearanceBody1"
android:textColor="?attr/colorOnBackground"
app:layout_constraintBottom_toBottomOf="@+id/materialTextView3"
app:layout_constraintStart_toEndOf="@id/barrier2"
app:layout_constraintTop_toTopOf="@+id/materialTextView3"
tools:text=": Google, Inc." />
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView9"
android:layout_
android:layout_
android:layout_marginStart="@dimen/keyline_2"
android:text="@`: ` + user.location"
android:textAppearance="?attr/textAppearanceBody1"
android:textColor="?attr/colorOnBackground"
app:layout_constraintBottom_toBottomOf="@+id/materialTextView4"
app:layout_constraintStart_toEndOf="@id/barrier2"
app:layout_constraintTop_toTopOf="@+id/materialTextView4"
tools:text=": Pittsburgh, PA, U.S.A." />
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView10"
formatNumberToTextWithColon="@1234"
android:layout_
android:layout_
android:layout_marginStart="@dimen/keyline_2"
android:textAppearance="?attr/textAppearanceBody1"
android:textColor="?attr/colorOnBackground"
app:layout_constraintBottom_toBottomOf="@+id/materialTextView5"
app:layout_constraintStart_toEndOf="@id/barrier2"
app:layout_constraintTop_toTopOf="@+id/materialTextView5"
tools:text=": 1,234" />
</androidx.constraintlayout.widget.ConstraintLayout>
当我点击 Android Studio Preview 上的“i”图标时，我会收到这些消息。
The following classes could not be instantiated:
- androidx.constraintlayout.widget.Barrier (Open Class, Show Exception, Clear Cache)
- androidx.constraintlayout.widget.ConstraintLayout (Open Class, Show Exception, Clear Cache)
- com.google.android.material.tabs.TabLayout (Open Class, Show Exception, Clear Cache)
- com.google.android.material.appbar.MaterialToolbar (Open Class, Show Exception, Clear Cache)
Tip: Use View.isInEditMode() in your custom views to skip code or show sample data when shown in the IDE. If this is an unexpected error you can also try to build the project, then manually refresh the layout.
Exception Details
java.lang.NoSuchFieldError: ConstraintLayout_Layout_barrierMargin
at androidx.constraintlayout.widget.Barrier.init(Barrier.java:204)
at androidx.constraintlayout.widget.ConstraintHelper.<init>(ConstraintHelper.java:85)
at androidx.constraintlayout.widget.Barrier.<init>(Barrier.java:123)
at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at org.jetbrains.android.uipreview.ViewLoader.createNewInstance(ViewLoader.java:403)
at org.jetbrains.android.uipreview.ViewLoader.loadClass(ViewLoader.java:186)
at org.jetbrains.android.uipreview.ViewLoader.loadView(ViewLoader.java:144)
at com.android.tools.idea.rendering.LayoutlibCallbackImpl.loadView(LayoutlibCallbackImpl.java:309)
at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:417)
at android.view.BridgeInflater.loadCustomView(BridgeInflater.java:428)
at android.view.BridgeInflater.createViewFromTag(BridgeInflater.java:332)
at android.view.LayoutInflater.createViewFromTag(LayoutInflater.java:961)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:1123)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:72)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:1097)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084)
at android.view.LayoutInflater_Delegate.parseInclude(LayoutInflater_Delegate.java:204)
at android.view.LayoutInflater.parseInclude(LayoutInflater.java:1161)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:1119)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:72)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:1097)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084)
at android.view.LayoutInflater.rInflate_Original(LayoutInflater.java:1126)
at android.view.LayoutInflater_Delegate.rInflate(LayoutInflater_Delegate.java:72)
at android.view.LayoutInflater.rInflate(LayoutInflater.java:1097)
at android.view.LayoutInflater.rInflateChildren(LayoutInflater.java:1084)
at android.view.LayoutInflater.inflate(LayoutInflater.java:682)
at android.view.LayoutInflater.inflate(LayoutInflater.java:501)
at com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate(RenderSessionImpl.java:328)
at com.android.layoutlib.bridge.Bridge.createSession(Bridge.java:373)
at com.android.tools.idea.layoutlib.LayoutLibrary.createSession(LayoutLibrary.java:141)
at com.android.tools.idea.rendering.RenderTask.createRenderSession(RenderTask.java:678)
at com.android.tools.idea.rendering.RenderTask.lambda$inflate$8(RenderTask.java:809)
at java.util.concurrent.CompletableFuture$AsyncSupply.run(CompletableFuture.java:1604)
at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)
at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)
at java.lang.Thread.run(Thread.java:748)
这是我的 build.gradle 文件中的依赖项。
apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: 'kotlin-kapt'
android
compileSdkVersion 29
buildToolsVersion "29.0.2"
defaultConfig
applicationId "com.mobile.githubuser"
minSdkVersion 26
targetSdkVersion 29
versionCode 1
versionName "1.0"
testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
buildTypes
release
minifyEnabled false
proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
dataBinding
enabled = true
android.sourceSets.all
java.srcDir('src/main/kotlin')
dependencies
implementation fileTree(dir: 'libs', include: ['*.jar'])
implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$rootProject.kotlinVersion"
implementation "androidx.appcompat:appcompat:$rootProject.appCompatVersion"
implementation "androidx.core:core-ktx:$rootProject.coreKtxVersion"
implementation "androidx.constraintlayout:constraintlayout:$rootProject.constraintLayoutVersion"
implementation "androidx.viewpager2:viewpager2:$rootProject.viewPagerVersion"
implementation "com.google.android.material:material:$rootProject.mdcVersion"
implementation "com.github.bumptech.glide:glide:$rootProject.glideVersion"
版本位于项目 gradle 文件中，可在此处查看。
// Top-level build file where you can add configuration options common to all sub-projects/modules.
buildscript
ext
kotlinVersion = '1.3.72'
mdcVersion = '1.2.0-alpha03'
constraintLayoutVersion = '2.0.0-beta1'
appCompatVersion = '1.1.0-alpha03'
coreKtxVersion = '1.3.0'
viewPagerVersion = '1.0.0'
glideVersion = '4.11.0'
repositories
google()
jcenter()
dependencies
classpath 'com.android.tools.build:gradle:4.0.1'
classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion"
// NOTE: Do not place your application dependencies here; they belong
// in the individual module build.gradle files
allprojects
repositories
google()
jcenter()
task clean(type: Delete)
delete rootProject.buildDir
我试过了。
同时安装适用于 Android 10.0 和 Android 8.1 的 SDK 我曾多次尝试使项目无效并重新启动 我已尝试多次清理和重建项目 我将我的 Android Studio IDE 更新到 4.0.1 更改我的 XML 中的主题（尽管这不是必需的）我正在使用约束布局版本2.0.0-beta1 来使用 MotionLayout。以前，当我使用版本1.1.3（稳定版）时，预览效果很好，即它可以渲染ConstraintLayout。但是，即使我使用约束布局版本1.1.3，像MaterialToolbar 和ShapeableImageView 这样的MDC 组件也总是无法渲染。我的依赖项中是否存在不兼容性？我该如何解决这个问题？
【问题讨论】：
您是否尝试过更改渲染引擎？Settings ➡ Experimental ➡ Use new Layout Rendering Engine
@知道我有。新的实验布局渲染引擎和旧的我都试过了。
您是否尝试刷新布局或清理项目？
@WahdatKashmiri 两者都是。
【参考方案1】：
首先，如果您将 ViewDataBiding 用于外部布局，那么您也可以将 ViewDataBinding 用于内部布局。
constarintLayoutVersion '2.0.0-beta1' 存在主要问题。如果您使用稳定版本 1.1.3 则可以使用。
<?xml version="1.0" encoding="utf-8"?>
<layout 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">
<data>
<variable
name="user"
type="com.harman.uilearning.ViewModel" />
</data>
<androidx.constraintlayout.widget.ConstraintLayout
android:layout_
android:layout_
app:layout_constraintEnd_toEndOf="parent"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent">
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView3"
android:layout_
android:layout_
android:drawableStart="@android:drawable/arrow_down_float"
android:drawablePadding="10dp"
android:text="Company Label"
android:textAlignment="center"
android:textAppearance="?attr/textAppearanceBody1"
android:textColor="?attr/colorOnBackground"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toTopOf="parent"/>
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView4"
android:layout_
android:layout_
android:layout_marginTop="10dp"
android:drawableStart="@android:drawable/arrow_down_float"
android:drawablePadding="10dp"
android:text="location_label"
android:textAlignment="center"
android:textAppearance="?attr/textAppearanceBody1"
android:textColor="?attr/colorOnBackground"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/materialTextView3"/>
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView5"
android:layout_
android:layout_
android:layout_marginTop="10dp"
android:drawableStart="@android:drawable/arrow_down_float"
android:drawablePadding="10dp"
android:text="repository_label"
android:textAlignment="center"
android:textAppearance="?attr/textAppearanceBody1"
android:textColor="?attr/colorOnBackground"
app:layout_constraintStart_toStartOf="parent"
app:layout_constraintTop_toBottomOf="@+id/materialTextView4"/>
<androidx.constraintlayout.widget.Barrier
android:id="@+id/barrier2"
android:layout_
android:layout_
android:layout_margin="5dp"
app:barrierDirection="right"
app:constraint_referenced_ids="materialTextView3,materialTextView4,materialTextView5" />
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView8"
android:layout_
android:layout_
android:layout_marginStart="10dp"
android:text="user.organizations"
android:textAppearance="?attr/textAppearanceBody1"
android:textColor="?attr/colorOnBackground"
app:layout_constraintBottom_toBottomOf="@+id/materialTextView3"
app:layout_constraintStart_toEndOf="@id/barrier2"
app:layout_constraintTop_toTopOf="@+id/materialTextView3"
app:layout_constraintEnd_toEndOf="parent"
tools:text=": Google, Inc." />
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView9"
android:layout_
android:layout_
android:layout_marginStart="10dp"
android:text="user.location"
android:textAppearance="?attr/textAppearanceBody1"
android:textColor="?attr/colorOnBackground"
app:layout_constraintBottom_toBottomOf="@+id/materialTextView4"
app:layout_constraintStart_toEndOf="@id/barrier2"
app:layout_constraintTop_toTopOf="@+id/materialTextView4"
app:layout_constraintEnd_toEndOf="parent"
tools:text=": Pittsburgh, PA, U.S.A." />
<com.google.android.material.textview.MaterialTextView
android:id="@+id/materialTextView10"
android:layout_
android:layout_
android:layout_marginStart="10dp"
android:textAppearance="?attr/textAppearanceBody1"
android:textColor="?attr/colorOnBackground"
app:layout_constraintBottom_toBottomOf="@+id/materialTextView5"
app:layout_constraintStart_toEndOf="@id/barrier2"
app:layout_constraintTop_toTopOf="@+id/materialTextView5"
app:layout_constraintEnd_toEndOf="parent"
tools:text=": 1,234" />
</androidx.constraintlayout.widget.ConstraintLayout>
</layout>
【讨论】：
我必须使用版本2.0.0-beta1，正如我的问题中所解释的那样才能使用 MotionLayout。 MotionLayout 在 1.1.3 中不可用。
您好，我添加了内部布局 xml，它几乎没有更改，只是将缺少的属性添加到您的布局并将约束布局版本更新为 2.0.0-beta3。随着这些变化。我可以看到预览
这很奇怪。我已将包含的布局修改为数据绑定布局，但预览仍然不适合我。此外，来自 MDC 的其他类也不起作用（例如 MaterialToolbar）。
你能解释一下你做得更好吗？【参考方案2】：
尝试使用 'def' 关键字声明，或者直接在依赖项中直接硬编码版本，我觉得 gradle 同步存在一些问题，
ext
def kotlinVersion = '1.3.72'
def mdcVersion = '1.2.0-alpha03'
def constraintLayoutVersion = '2.0.0-beta1'
def appCompatVersion = '1.1.0-alpha03'
def coreKtxVersion = '1.3.0'
def viewPagerVersion = '1.0.0'
def glideVersion = '4.11.0'
或
dependencies
...
implementation "androidx.constraintlayout:constraintlayout:2.0.0-beta1"
【讨论】：
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