Of course there are situations where you want to reduce every millisecond.Īlthough you should beaware of micro benchmarks you could try this just to get a rough idea: import. So, once you found what method to invoke, you just keep a reference to it, and consecutive invocations works similarly. What is costly is the method lookup, but method invocation once is very similar. So obviously I'm wondering, if I write a library that does something vaguely similar, are there tricks I need to know about? Because it appears you can't get away from some amount of reflection, on each call. But reflection is not well suited for code on the critical path in. If your task description includes words such as 'adapter' or 'decorator,' then reflection may be a good fit. This improvement in empirical soundness is accompanied by increased performance relative to Elf, demonstrating that near-sound handling of reflection is. have relatively large startup cost and are super fast after that. Reflection is best suited for writing 'glue'code that sits at the boundaries between disparate classes, packages, and subsystems. I've definitely noticed that Gson/Jackson etc. Or is there some way to pay (all) the cost of reflection only at startup? I can understand how the library might internally cache the Field objects, but it seems to me that it needs to reflectively instantiate the object each time, and it needs to call the setter on each field (reflectively) based on the parsed value from the json. the lambda support and performance improvements in other JVM languages, such as JRuby). MyObject obj = new Gson().fromJson(someInputStream, MyObject.class) Reflection was introduced in Java 1.1 (circa February 1997). My question is, how do they do it? Is there some "tricks" to know or do they simply use straight reflection, and the performances worries are overblown? Many (if not all) libraries provide good (or great) performance even though they use reflection. Java Reflection Performance, but my particular question is, it seems that many popular libraries are implemented via annotations and reflection (Gson, Jackson, Jaxb implementations, hibernate search, for example). So I know this topic has been done before, e.g.
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