This line is needed

app/build.gradle

@@ -17,9 +17,10 @@ android {
             proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
         }
     }
+    buildToolsVersion '27.0.3'
 }
 
 dependencies {
-    implementation fileTree(dir: 'libs', include: ['*.jar'])
+    implementation fileTree(include: ['*.jar'], dir: 'libs')
-    implementation "com.android.support:support-v4:26.1.0"
+    implementation 'com.android.support:support-v4:26.1.0'
 }