Why engine instanceof GroovyScriptEngineImpl ?

Question

in groovy while getting the ScriptEngine using java6 feature, for groovy it gives me instance "GroovyScriptEngineImpl" which a type of class not an interface, is there any other way to get the interface ?

ScriptEngineManager  factory = new ScriptEngineManager();
ScriptEngine engine = factory.getEngineByName("groovy");
assert engine instanceof GroovyScriptEngineImpl

is there any interface available instaed of using "GroovyScriptEngineImpl"

Answer 1

GroovyScriptEngineImpl implements the Compilable, Invocable, and ScriptEngine interfaces.