Default interface methods are only supported starting with Android 7.0 (Nougat)

As CommonsWare mentioned, for reference add this inside the android {...} closure in the build.gradle for your app module (app level) to resolve the 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 menu 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 the app-level Gradle file, you have to write this 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