Java Preprocessor Check OS

Question

How do I use Java preprocessors to determine what OS I am compiling on?

@James: [spp](http://hg.openjdk.java.net/jdk6/jdk6/jdk/file/tip/make/tools/src/build/tools/spp/Spp.java), of course! ;-) — Chris Jester-Young, Dec 01 '11 at 22:56

score 1 · Answer 1 · edited May 23 '17 at 10:33

1

Try this:

System.getProperty("os.name")

From How do I programmatically determine operating system in Java?

BTW Java doesn't have a preprocessor...one of the annoying things I discovered.

edited May 23 '17 at 10:33

Community

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answered Jan 07 '11 at 02:31

FeifanZ

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That will return the OS at *runtime*, not compile time. – Lawrence Dol Jan 07 '11 at 02:43
Hm...good point...but I guess I was thinking that if you're running the compiler, then chances are you'll know what OS the compiler is running on... – FeifanZ Jan 07 '11 at 02:46

score 1 · Answer 2 · answered Jan 07 '11 at 02:46

There is no Java preprocessor and no ability to conditionally compile.

There is a very primitive debugging feature built in whereby the compile is allowed to delete conditional blocks with a constant condition which is false to facilitate elimination of debug code - but I don't recall if the spec requires or allows the code to be deleted from the compiled class.

static final boolean DEBUG=false;


...


if(Debugging.DEBUG) {
    // some code which the compile may (or must?) eliminate
    }

If you want to detect the O/S at runtime and do different things on different platforms, there are a number of system properties required in every JVM which are documented in System.getProperties(). See the JavaDoc, relative it's installed or network location:

api/java/lang/System.html#getProperties()

Java Preprocessor Check OS

2 Answers2