Telling the Compiler to Skip Code Pieces

Question

Hey all,
I'm using a 3rd party library in my code, which works fine (setting the classpath, compiling, running, etc) as long as the corresponding 3rd party jar file exists.
However, I want to basically say "if that file doesn't exist, instead of throwing a compiler error, just skip this bit here". No crucial programming logic requires the library (in fact it's only 3 lines or so that use it to pop up a BalloonTip), so just skipping over it shouldn't affect anything else.
I'm pretty sure nothing like this exists, but I figured I'd double check anyway. Creating an SSCCE for this is by definition impossible, but here's a glimpse into what I'd hope would exist in a perfect world:
public class Project{
   public static void main(String [] args){
      System.out.println("Starting the program, attempting to do third party something...");
      @OnlyCompileIf ( some.other.package.exists() )
            some.other.package.ThirdPartyObject.doSomething();
            System.out.println("Successfully did third party something!");
      System.out.println("Continuing with the program...");
      //rest of program logic..
}I know that's pretty far-fetched, but I figured I'd throw it out there anyway. The idea is this: just in case a user has not downloaded that third party jar file, my program should still work without it, just minus the little pop ups. Any thoughts?

Answer 1

sabre150 wrote:
Since you are using Ant, you can copy the source file and use a filter to remove the offending lines as you copy.
If the built-in filters do not do what you want then it is easy to write your own.
Edited by: sabre150 on Jul 17, 2009 6:07 PMThat seems just about perfect. I've been trying to use the examples on that link and others I've found through googling, but for some reason I can't even get ant to replace a single word in my program (I'm trying to test it out just be removing a dummy comment for now). It prints out a message saying it's performing the copy operation, but nonetheless the strings are persistent.
I'm giving up for the day and calling it a week; I'll start hacking away at it again on Monday morning. I know this isn't the place to debug ant scripts, but if you can spot anything wrong with this, I'd definitely appreciate it:
<target name="removeTest" unless="OtherJar.present">
     <echo message="Ant is removing the string."/>
     <copy file="src/Test.java" toFile="src/Test.java" filtering="true" overwrite="true">
          <filterset>
               <filter token="testing" value="replaced"/>
          </filterset>
     </copy>
     <echo message="copied"/>
</target>I have a comment that just says //testing in my java class. Ant is printing out messages saying that it's copying the file, but when I reopen my file, nothing has changed. Argh!
DrClap wrote:
Right... so are you saying you're sending out your source code for the user to compile? If that's the case then you ought to assume the user is technically >competent enough to download the dependencies. (Which you would document, of course.) You don't have to sugar-coat things for people who are using Java >compilers.That's true, and if I can't get this working, that'll be the story I stick to. But I'd much rather have my program be absolutely fool-proof and work cleanly without the third party jar instead of not even compiling. I'm going to have nightmares this weekend about 50,000 people coming to me and asking why my program doesn't compile for them...
Anyway, thanks for all the suggestions. Hopefully by Monday everything will make a bit more sense >:(