Running Java Code from Within Java [duplicate]

Question

Possible Duplicates:
using eval in Java
Loading external source code and using them internally (by re-compiling or something)

I want to simulate an 'eval' in Java such that the function takes in a String (some source code), compiles it, runs it, and spits back the return value.

I know I can compile it using the JavaCompiler API, but I am unsure the best way to actual run the code like this. Runtime.exec feels too heavy for this task... I don't want to spawn another java process each time I run this 'eval' function just to evaluate '30+20' or something. This would be slow and resource intensive.

Finally, this must be able to run ANY java code, so relying on a scripting language evaluator inside Java won't do (ex. if the input is more complex Java than just '30+20')

Any alternatives?

Also possible dup of How could I call Java code dynamically ? — Matt Ball
– Matt Ball, Commented Dec 10, 2010 at 4:17

AlanObject · Accepted Answer · 2010-12-10 04:15:39Z

0

I have never done this myself, but you can write your own ClassLoader and load the bytecodes into the JVM. There is a tutorial on this.

answered Dec 10, 2010 at 4:15

AlanObject

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