Question: While using google map activity in my android application I get this error.

**"Could not resolve com.google.android.gms:play-services:11.8.0."**

**Project level** Gradle file:

```
buildscript {

repositories {
    jcenter()
    google()
}
dependencies {
    classpath 'com.android.tools.build:gradle:3.0.1'

    // NOTE: Do not place your application dependencies here; they belong
    // in the individual module build.gradle files
}
}
allprojects {
    repositories {
        jcenter()
        google()
    }
}
task clean(type: Delete) {
    delete rootProject.buildDir
}

```

**Application level** Gradle file:

```
dependencies {
    compile fileTree(include: ['*.jar'], dir: 'libs')
    androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
        exclude group: 'com.android.support', module: 'support-annotations'
    })
    compile 'com.android.support.constraint:constraint-layout:1.0.2'
    testCompile 'junit:junit:4.12'
    //noinspection GradleCompatible
    implementation 'com.android.support:appcompat-v7:26.1.0'
    implementation 'com.google.android.gms:play-services:11.8.0'
}

```

Answer: 
So, finally I got the answer, 

I've turned on gradle offline mode that's why it could not find out cached files for that version play-service. 

I turned it off (under File-Settings-Build,Execution,Deployment-Gradle) and again sync project and some files have been downloaded then it works now.
You need to include this *class path* inside project level *gradle*.

```
classpath 'com.google.gms:google-services:3.0.0'

```

As well as inside app level *build.gradle*.

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

```