更新到 Android 3.1.3 时找不到符号 R

Question

昨天我将 Android 更新到 Android 3.1.3，一切都还不错，直到今天我创建了一个新的 Empty Activity 并且在“AppCompatActivity”上显示错误“找不到符号”，所以我搜索并阅读它与“build.gradle”有关，所以我一直在更新库并得到不同的错误，最新的一个是对象“R”无法解析符号。所以这就是我所拥有的。

我已经多次尝试解决它（如您在代码中看到的 cmets），但到目前为止我还没有解决它。请帮我！

还有一个部分，Android 建议我将 gradle.properties # org.gradle.parallel=true 从 false 更改，但它也不起作用。

build.gradle

buildscript {
    repositories {
        jcenter()
        google()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.1.3'
        //classpath 'com.android.tools.build:gradle:2.1.3'
        //classpath 'com.android.tools.build:gradle:3.2.0-alpha17'
        //classpath 'com.android.tools.build:gradle:3.1.3'
        //classpath 'com.google.gms:google-services:3.2.0'
        //classpath 'com.android.tools.build:gradle:3.1.3'
        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}
allprojects {
    repositories {
        jcenter()
        maven {
            url 'https://maven.google.com/'
            //name 'Google'
        }
    }
}

依赖

android {
    compileSdkVersion 23
    buildToolsVersion '24.0.2'

    defaultConfig {
        applicationId "com.example.dell.getspeed"
        minSdkVersion 14
        targetSdkVersion 23
        versionCode 1
        versionName "1.0"
    }

dependencies {

    compile fileTree(include: ['*.jar'], dir: 'libs')
    testCompile 'junit:junit:4.12'
    //compile 'com.google.android.gms:play-services:8.3.0'
    compile 'com.android.support:appcompat-v7:23.4.0'
    compile 'com.android.support:design:23.4.0'
    compile 'com.android.support:support-v4:23.4.0'
    compile 'org.jbundle.util.osgi.wrapped:org.jbundle.util.osgi.wrapped.org.apache.http.client:4.1.2'
    compile 'net.gotev:uploadservice:2.1'
    compile 'com.mcxiaoke.volley:library-aar:1.0.1'
    compile 'com.google.android.gms:play-services-maps:9.8.0'
    compile 'com.android.support:cardview-v7:23.4.0'
    compile 'com.android.support:recyclerview-v7:23.4.0'

    /*implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation 'com.android.support:appcompat-v7:27.1.0'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'


    /*implementation 'com.android.support.constraint:constraint-layout:1.1.2'
    //implementation 'com.android.support:appcompat-v7:27.1.0'
    //implementation 'com.android.support:design:26.4.0'
    compile fileTree(dir: 'libs', include: ['*.jar'])
    testCompile 'junit:junit:4.12'
    compile 'com.android.support:appcompat-v7:25.4.0'
    compile 'com.github.anastr:speedviewlib:1.2.0'
    compile 'com.android.support:design:25.4.0'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
    //compile 'com.android.support.constraint:constraint-layout:1.1.2'*/
}

gralde-wrapper.propierties

distributionUrl=https\://services.gradle.org/distributions/gradle-2.14.1-all.zip
#distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-all.zip
#distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-all.zip

日志： Logs

Answer 1

关闭项目并再次导入。今天为我工作。

或

由于某种原因，这些属性在 26 个库中不再存在。为了增加这些库，您还必须将 compileSdk 增加到 27。很可能您还必须下载 sdk 27​​

短版，后续继续应用`graddle``

将compile 更改为implementation

    apply plugin: 'com.android.application'

android {
    compileSdkVersion 27
    defaultConfig {
        applicationId "cl.cutiko.testingupdate"
        minSdkVersion 21
        targetSdkVersion 27
        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-v7:27.1.0'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    implementation 'com.android.support:design:27.1.0'
    testImplementation 'junit:junit:4.12'
    androidTestImplementation 'com.android.support.test:runner:1.0.1'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
}

build.gradle（项目）

buildscript {

    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.1.0'


        // 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
}

Answer 2

distributionUrl=https\://services.gradle.org/distributions/gradle-4.4-all.zip

classpath 'com.android.tools.build:gradle:3.1.3'

compileSdkVersion 27
minSdkVersion 16
targetSdkVersion 27

implementation 'com.android.support:appcompat-v7:23.4.0'
implementation 'com.android.support:design:23.4.0'
implementation 'com.android.support:support-v4:23.4.0'
implementation 'com.android.support:recyclerview-v7:23.4.0'

文件 - 使缓存无效/重新启动 - 无效并重新启动

Answer 3

关闭当前项目并再次重新打开它并重建解决方案。大多数时候通过重建解决方案， “R无法解决”的问题可以解决。