Can you detect in Java if the code is being debugged? [duplicate]

Question

Possible Duplicate:
How to find out if “debug mode” is enabled

Coming from C#, I cannot believe that Java has no way to execute code only when the program is being debugged. Somehow, Log4J seems to be able to do it. Does anyone know a possibility for this? I'm thinking of something like this:

#if DEBUG
    executedCode();
#endif

Or something like this:

if (Java.isDebugging())
    executeCode();

Ideas?

EDIT: Thanks to Matt Ball, the code in this possible duplicate works:

public static boolean debugging = java.lang.management.ManagementFactory.getRuntimeMXBean().
        getInputArguments().toString().indexOf("-agentlib:jdwp") > 0;

Answer 1

I think you are conflating a debug build of a program with running under the debugger (unless C# is rather strange).

Many systems - including lots of C/C++ build environments, and I expect C#, given the way Microsoft has historically designed the Visual Studio build processes - have two different types of builds you can do:

• Release build, with only info/error/warning logging, no debug symbols, extra optimizations, etc.
• Debug build, with extra logging enabled, debug symbols, possibly tuned-down optimizations.

You use debug builds while developing and debugging your program, and release builds for final QA and release. The debug builds, however, are independent of being run under a debugger - they're normal programs, and if you run them the run and still output their extra logging information. This can be very useful.

Running them under a debugger is completely orthogonal. You can run the release build under a debugger (although, lacking debug symbols, it might not be very useful). In fact, I would submit that you do not want code to change based on whether you are running under a debugger - it makes it rather difficult to debug the code being actually run in the application.

And unlike C, C++, and C#, Java has no facility for compile-time conditionals, so everything is enabled in the program. You typically deal with this by having a very fast way to check if the debugging message is to be emitted, and doing as little work as possible in the case where it is not.

Answer 2

C doesn't execute code only when it is debugging, what you're showing is a conditional compile directive, the code only gets compiled when the flag value is true. The running code has no idea when it is being debugged. Likewise with Log4j it is reading from its configuration what level to use, it has no idea when it is being debugged.

Conditional compile flags were deliberately left out of Java, they wanted to avoid complexity. C# has a different philosophy.