问题
This question is more for furthering my knowledge than anything...
Does Java have anything similar to PHP's ability to generate a variable name? I have an SCJA Cert and I'm studying for the SCJP and have never seen this, but was curious.
PHP Example
$application->{$request->getParameter("methodCall")}($request->getParameter('value'));
Does Java have anything similar? I've been reading on here and the general answer is to use a HashMap which I'm not interested in since this isn't to solve a real problem. I'm more interested in the is this possible solution? If not so be it, but just trying to expand my knowledge!
Thanks, Jared
回答1:
No, variables (fields and local variables) are statically "created" at compile-time in Java.
Of course memory is only ever occupied at runtime, but how many and which fields an object has is decided at compile-time.
Therefore you can't "dynamically add a field" in Java.
And yes: A Map is the solution to the problem. "Adding a field" is not usually the problem but an attempted solution that's appropriate for some languages (usually dynamic ones) and inappropriate for others.
回答2:
I think you mean a field in a class. A local variable can only be used in a method.
To generate a field in a class or a variable, you need to generate Java code and compile it or byte code at runtime. It can be done but is 100x more complicated than using a simple Map. (I have done it dynamically before and I wouldn't recommend it unless you really have to)
If you want to do code generation I would suggest using Objectweb's ASM.
回答3:
This can't be done...Java Reflection only allows you to view the structure of a class but not append to it.
来源：https://stackoverflow.com/questions/5885669/dynamic-java-variable-naming