Simple way to get wrapper class type in Java

Question

I have a piece of code where I need to pass the class of a field in a method. Because of the mechanics of my code I can only handle reference objects and not primitives. I w

Answer 1

With a more recent jdk, this is a one-liner now:

@SuppressWarnings("unchecked")
public static  Class wrap(Class c) {
    return (Class) MethodType.methodType(c).wrap().returnType();
}

@SuppressWarnings("unchecked")
public static  Class unwrap(Class c) {
    return (Class) MethodType.methodType(c).unwrap().returnType();
}

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Here is a test that I wrote using JMH and here are the results:

Benchmark                        Mode  Cnt   Score   Error  Units
PrimitiveToWrapper.ifStatements  avgt   30  42.112 ± 0.716  ns/op
PrimitiveToWrapper.map           avgt   30  45.018 ± 0.923  ns/op
PrimitiveToWrapper.wrap          avgt   30  52.369 ± 0.836  ns/op

The difference is rather small.