[pgrulich]

So for getters and setters a Jit can inline the function call and in the end you have a direct memory access. In your example you have to cast because URLConnection could be a HttpURLConnection or JarURLConnection. But again a good Jit would speculate that it is always a HttpURLConnection and deoptimize if not.

[imtringued]

The JVM also has full information about the class hierarchy at runtime. If you add a class that overrides a function it will deoptimize that overriden function to a virtual function but otherwise the JVM will just treat it as a static function and inline it if necessary.