Default interface methods are only supported starting with Android N

As CommonsWare mentioned, for reference add this inside the android {...} closure in the build.gradle for your app module to resolve issue:

android {
...
  compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
...
}

You should use Java 8 to solve this, based on the Android documentation you can do this by

clicking File > Project Structure

and change Source Compatibility and Target Compatibility.

and you can also configure it directly in the app-level build.gradle file:

android {
  ...
  // Configure only for each module that uses Java 8
  // language features (either in its source code or
  // through dependencies).
  compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
  }
}

In app-level gradle, you have to write these code:

android {
...
  compileOptions {
    sourceCompatibility JavaVersion.VERSION_1_8
    targetCompatibility JavaVersion.VERSION_1_8
  }
}

They come from JavaVersion.java in Android.

An enumeration of Java versions.

Before 9: http://www.oracle.com/technetwork/java/javase/versioning-naming-139433.html

After 9: http://openjdk.java.net/jeps/223

@canerkaseler