How to specify source and target compatibility in Java module?

Question

I have a Gradle project consisting of an Android module (the com.android.library plugin is applied in the build.gradle file) and a Java module (the

Answer 1

Compatibility needs to be specified inside the compileJava block

compileJava   {
  sourceCompatibility = '1.8'
  targetCompatibility = '1.8'
}

IntelliJ gives this warning

Access to 'sourceCompatibility' exceeds its access rights

if you use a double parameter.

When you make the value a string (e.g. quoted) the warning will disappear.

--edit--

the warning only appears using 1.8 in IntelliJ 2016. In 2017 the warning is gone using either 1.8 or '1.8'