Java
A concurrent, class-based, object-oriented, language specifically designed to have as few implementation dependencies as possible
22 Alternatives To Java
Clojure
Clojure is a dynamic, general-purpose programming language, combining the approachability and interactive development of a scripting language with an efficient and robust infrastructure for multithreaded programming.
Rust
A safe, concurrent, practical language. Rust is blazingly fast and memory-efficient: with no runtime or garbage collector, it can power performance-critical services, run on embedded devices, and easily integrate with other languages.