错误-SDK v3不能小于库中定义的SDKv4

Error-SDK V3 cannot be smaller than SDKv4 defined in Library

所以我在 Android Studio 上创建了一个应用程序,我试图在我的应用程序中植入 AdMob。完成后,我收到错误 Error-SDK V3 cannot be smaller than SDKv4 defined in Library。 这是我的 Build.Gradle

   apply plugin: 'com.android.application'
   android {
    compileSdkVersion 21
    buildToolsVersion "22.0.1"

    defaultConfig {
        applicationId "ru.o2genum.coregame"
        minSdkVersion 3
        targetSdkVersion 8
    }

    dependencies {
        compile 'com.google.android.gms:play-services-ads:7.8.0'
        compile 'com.android.support:support-v4:20.+'
        compile 'com.google.android.gms:play-services:+'
        //compile 'com.android.support:support-v4:20.0.0'
        //compile 'com.google.android.gms:play-services:5.0.77'
    }

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

这里是错误 Error:(24, 5) uses-sdk:minSdkVersion 3 cannot be smaller than version 9 declared in library C:\Users\Osama\StudioProjects\CoreGame-master\app\build\intermediates\exploded-aar\com.google.android.gms\play-services-ads.8.0\AndroidManifest.xml

您正在使用 google 播放服务库,其 minSdk 版本为 9,但在您应用的 gradle 文件中您已将其指定为 3。因此您必须将其更改为9. 修改如下,

defaultConfig {
    applicationId "ru.o2genum.coregame"
    minSdkVersion 9
    targetSdkVersion 9
}