IAmYourFaja IAmYourFaja - 6 months ago 24
Java Question

What is the difference between a.getClass() and A.class in Java?

In Java what pros/cons exist surrounding the choice to use

a.getClass()
or
A.class
? Either can be used wherever a
Class<?>
is expected, but I imagine that there would be performance or other subtle benefits to using both in different circumstances (just like there are with
Class.forName()
and
ClassLoader.loadClass()
.

Answer

I wouldn't compare them in terms of pros/cons since they have different purposes and there's seldom a "choice" to make between the two.

  • a.getClass() returns the runtime type of a. I.e., if you have A a = new B(); then a.getClass() will return the B class.

  • A.class evaluates to the A class statically, and is used for other purposes often related to reflection.

In terms of performance, there may be a measurable difference, but I won't say anything about it because in the end it is JVM and/or compiler dependent.