What is the cloest thing to a function pointer in java? [duplicate]

Question

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What's the nearest substitute for a function pointer in Java?

I just have a situation where it would be nice to have the functionality of something similar to function pointers like you might use in c or c++. The best thing I can think of is combining Runnables and launch them in a different thread. Suggestions?

Answer 1

Until they add closures to java, the thing seems closest to java.lang.reflect.Method. For example Method method = SomeClass.getMethod("methodName", methodParameterTypes)

Then you can pass the method around (like a function pointer) and call invoke(..) on it, passing an object (or null if static)

But this is not quite a good practice. You can define an interface, or use an existing one Runnable / Callable, implement it inline, and pass the instance.

Answer 2

Use Functors, aka Function Objects.

Java has no first-class functions, so function objects are usually expressed by an interface with a single method (most commonly the Callable interface), typically with the implementation being an anonymous inner class.