Especially before Java 8, writing Java code was very painful compared with Groovy, even though Groovy was fairly slower, and its compiler buggy. Groovy has clos

Especially before Java 8, writing Java code was very painful compared with Groovy, even though Groovy was fairly slower, and its compiler buggy. Groovy has closures, AST transformations builtin, much nicer syntax for properties (backed by getters/setters), ability to sort-of change classes at runtime (without instrumentation), multiple dispatch (i.e. dispatch based on the runtime type of the arguments), the ability to use reflection without the awful reflection API and so on.