我在这里看到了很多这样的问题，他们都有相同的答案，确保你有

compile 'com.android.support:cardview-v7:26.0.0'

在你的 build.gradle 文件中，并确保你在你的 xml 中使用完全限定的名称......

<android.support.v7.widget.CardView

我在我的 xml 文件中使用它，我的 build.gradle 文件中有编译行。该应用程序编译，但每当我在模拟器上运行该应用程序时，我单击按钮启动 ShowImagesActivity，它崩溃并显示消息“在路径上找不到类‘android.support.v7.widget.CardView’... "

这是我的 layout_images.xml 文件...

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
              android:orientation="vertical"
              android:layout_width="match_parent"
              android:layout_height="match_parent">

    <adroid.support.v7.widget.CardView
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_margin="8dp"
        android:padding="8dp">
        <RelativeLayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:minHeight="100dp">
            <TextView
                android:id="@+id/textViewName"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:text="Name"
                android:textAlignment="center" />
            <ImageView
                android:id="@+id/imageView"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:layout_below="@id/textViewName" />
        </RelativeLayout>
    </adroid.support.v7.widget.CardView>

</LinearLayout>

这是我的 build.gradle 文件，应用程序一个...

apply plugin: 'com.android.application'
check.dependsOn 'assembleMinSdkJellybeanDebugAndroidTest', 'assembleMinSdkIcsDebugAndroidTest'

android {
    compileSdkVersion 26
    buildToolsVersion '26.0.0'
    flavorDimensions "minSdkVersion"

    defaultConfig {
        applicationId "com.google.firebase.quickstart.auth"
        minSdkVersion 26
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner 'android.support.test.runner.AndroidJUnitRunner'
    }

    buildTypes {
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    lintOptions {
        abortOnError false
    }

    productFlavors {
        // Build variant with minSdk 16 to include Facebook and FirebaseUI libraries.
        minSdkJellybean {
            dimension "minSdkVersion"
            minSdkVersion 16
        }
        // Build variant with minSdk 14, excludes Facebook and FirebaseUI libraries.
        minSdkIcs {
            dimension "minSdkVersion"
            minSdkVersion 16
        }
    }
}

configurations.all {
    resolutionStrategy.force 'com.android.support:support-annotations:26.0.0'
}

dependencies {
    // Firebase Authentication
    // Google Sign In SDK (only required for Google Sign In)
    // Firebase UI
    // Used in FirebaseUIActivity. The FirebaseUI-Android library has a minSdk level of 16
    // so this library is only included in the minSdkJellybean variant.
    // Facebook Android SDK (only required for Facebook Login)
    // Used in FacebookLoginActivity. This is only compiled into the minSdkJellybean variant of this
    // app. You can build a 'minSdkGingerbread' variant to test on devices with 9 <= SDK <= 15.
    // Twitter Android SDK (only required for Twitter Login)
    compile('com.twitter.sdk.android:twitter-core:1.6.6@aar') {
        transitive = true
    }
    compile('com.twitter.sdk.android:twitter:1.13.1@aar') {
        transitive = true
    }
    compile 'com.google.firebase:firebase-storage:11.2.0'
    compile 'com.google.firebase:firebase-storage:11.2.0'
    compile 'com.android.support:appcompat-v7:26.0.0'
    compile 'com.android.support:animated-vector-drawable:26.0.0'
    compile 'com.android.support:cardview-v7:26.0.0'
    compile 'com.android.support:recyclerview-v7:26.0.0'
    compile 'com.android.support:design:26.0.0'
    compile 'com.firebaseui:firebase-ui:2.3.0'
    compile 'com.google.firebase:firebase-auth:11.2.0'
    compile 'com.google.android.gms:play-services-auth:11.2.0'
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    compile 'com.google.firebase:firebase-database:11.2.0'
    androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2.2'
    androidTestCompile 'com.android.support.test:runner:0.5'
    minSdkJellybeanCompile 'com.facebook.android:facebook-android-sdk:4.9.0'
    minSdkJellybeanCompile 'com.android.support:customtabs:26.0.0'
}

apply plugin: 'com.google.gms.google-services'

在我的代码中我正在使用

@Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View                    v          = LayoutInflater.from(parent.getContext()).inflate(R.layout.layout_images, parent, false);
        ViewHolder viewHolder = new ViewHolder(v);
        return viewHolder;
    }

我拥有所有其他帖子所说的我需要的一切，我的 build.gradle 中的编译行和我的 xml View 中的完全限定名称，并且该应用程序编译完美，每当我尝试运行它时它就会崩溃单击启动 ShowImagesActivity 的按钮后的模拟器。如果找不到类，它不应该编译失败吗？是否有任何其他解决方案，或者任何人都可以看到任何会导致应用程序因找不到类(class)而崩溃的错误吗？谢谢。

最佳答案

我遇到了同样的问题，但我的库已更新为 androidX

implementation 'androidx.cardview:cardview:1.0.0'

因此我的问题通过使用标签解决了

<androidx.cardview.widget.CardView/>

关于java - 没有找到类 "android.support.v7.widget.CardView"，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/46370607/