Question

我是Android Studio的新手，正在尝试创建新的工具栏，但是却收到“ java.lang.ClassNotFoundException”：我在下面找到了可能的解决方案，但我不想将compileSdkVersion和targetSdkVersion从28降级到27。

android.view.View$OnUnhandledKeyEventListener

我什至没有在“ MainActivity.java”中编写任何代码。我刚刚创建了toolbar_layout.xml，无法预览任何内容！

如何解决此预览错误？

styles.xml

<resources>

    <!-- Base application theme. -->
    <style name="AppTheme" parent="Theme.AppCompat.Light.NoActionBar">
        <!-- Customize your theme here. -->
        <item name="colorPrimary">@color/colorPrimary</item>
        <item name="colorPrimaryDark">@color/colorPrimaryDark</item>
        <item name="colorAccent">@color/colorAccent</item>
    </style>

</resources>

build.gradle（Module：app）

apply plugin: 'com.android.application'

android {
    compileSdkVersion 28
    defaultConfig {
        applicationId "com.example.rob.toolbar"
        minSdkVersion 16
        targetSdkVersion 28
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.1.3'
    implementation 'com.android.support:design:28.0.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
}

MainActivity.java

package com.example.rob.toolbar;

import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;

public class MainActivity extends AppCompatActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
    }
}

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    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"
    tools:context=".MainActivity">

    <include
        layout="@layout/toolbar_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"/>

</RelativeLayout>

toolbar_layout.xml

<?xml version="1.0" encoding="utf-8"?>
<android.support.v7.widget.Toolbar
    android:id="@+id/toolbar_layout"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:background="@android:color/holo_red_dark">

</android.support.v7.widget.Toolbar>

异常消息：

java.lang.ClassNotFoundException：android.view.View $ OnUnhandledKeyEventListener 在org.jetbrains.android.uipreview.ModuleClassLoader.load（ModuleClassLoader.java:180）在com.android.tools.idea.rendering.RenderClassLoader.findClass（RenderClassLoader.java:61）在org.jetbrains.android.uipreview.ModuleClassLoader.findClass（ModuleClassLoader.java:118）在java.lang.ClassLoader.loadClass（ClassLoader.java:424）在java.lang.ClassLoader.loadClass（ClassLoader.java:357）在org.jetbrains.android.uipreview.ModuleClassLoader.loadClass（ModuleClassLoader.java:213）在android.support.v7.widget.ViewUtils.isLayoutRtl（ViewUtils.java:58）在android.support.v7.widget.Toolbar.onMeasure_Original（Toolbar.java:1578）在android.support.v7.widget.Toolbar.onMeasure（Toolbar.java）在android.view.View.measure_Original（View.java:22071）在android.view.View_Delegate.measure（View_Delegate.java:80）在android.view.View.measure（View.java:22035）在android.widget.RelativeLayout.measureChildHorizontal（RelativeLayout.java:715）在android.widget.RelativeLayout.onMeasure（RelativeLayout.java:461）在android.view.View.measure_Original（View.java:22071）在android.view.View_Delegate.measure（View_Delegate.java:80）在android.view.View.measure（View.java:22035）在android.view.ViewGroup.measureChildWithMargins（ViewGroup.java:6602）在android.widget.FrameLayout.onMeasure（FrameLayout.java:185）在android.view.View.measure_Original（View.java:22071）在android.view.View_Delegate.measure（View_Delegate.java:80）在android.view.View.measure（View.java:22035）在android.widget.RelativeLayout.measureChildHorizontal（RelativeLayout.java:715）在android.widget.RelativeLayout.onMeasure（RelativeLayout.java:461）在android.view.View.measure_Original（View.java:22071）在android.view.View_Delegate.measure（View_Delegate.java:80）在android.view.View.measure（View.java:22035）在com.android.layoutlib.bridge.impl.RenderSessionImpl.measureView（RenderSessionImpl.java:590）在com.android.layoutlib.bridge.impl.RenderSessionImpl.inflate（RenderSessionImpl.java:343）在com.android.layoutlib.bridge.Bridge.createSession（Bridge.java:384）在com.android.tools.idea.layoutlib.LayoutLibrary.createSession（LayoutLibrary.java:193）在com.android.tools.idea.rendering.RenderTask.createRenderSession（RenderTask.java:544）在com.android.tools.idea.rendering.RenderTask.lambda $ inflate $ 3（RenderTask.java:678）在java.util.concurrent.FutureTask.run（FutureTask.java:266）在java.util.concurrent.ThreadPoolExecutor.runWorker（ThreadPoolExecutor.java:1142）在java.util.concurrent.ThreadPoolExecutor $ Worker.run（ThreadPoolExecutor.java:617）在java.lang.Thread.run（Thread.java:745）

Android Studio 3.1.4：无法预览新的工具栏

0 个答案: