Inverse of Supplier<T> in Guava

Your alternatives are:

• Java 8 introduces a Consumer interface which you can compose.
• Xtend's standard library contains Procedures.
• Scala has Function*; if a function's return type is Unit, it is considered a side effect.

In all of these languages, you can use functional interfaces conveniently, so you could also use e.g. Functional Java's Effect.

Otherwise, you better rely on existing language constructs for performing side effects, e.g. the built-in for loop. Java < 8 inflicts tremendous syntactic overhead when using lambdas. See this question and this discussion.