Specifying classpath when executing another java program from within a java program

Question

I'm looking at an application and it has the following statements

executeProcess("java.exe -cp { 500-characters worth of stuff } someProg");

This is done several times through the program, since this application launches other programs to perform certain tasks. The previous developers decided to just copy and paste again and again as long as it works.

The problems I have with this are

1. it's redundant. That classpath is copied a dozen times. I can refactor it and move it to a single location, so that's easy to deal with for now and makes life easier for the next guy that might have to maintain this thing.

2. everytime a program adds a new dependency, I need to update the class path. All of our libraries are stored in a single folder (with subfolders for different libraries), so I can't just use wildcards because they do not check recursively: -cp "path/to/lib/*

Currently I'm the only one maintaining our entire tool set, so if I add a library, I know what to do to make it work, but in general this seems like bad practice.

What are some ways to make these process calls easier to manage?

Answer 1

I have had good experience with using ant and maven-ant-tasks for launching java applications without managing the classpath manually. Of course, in order to do that you would have to use maven for build/dependency management or at least install your jars to a local nexus instance.

The end user needs to checkout a maven project that declares a list of top level runtime dependencies (transitive dependencies will be resolved automatically, for libraries that are maven projects) that also contains some ant scripts with targets that execute the application.

You will have to figure out how the java application will know the actual location of the ant scripts (an env variable maybe?), but it's an extremely superior solution to manual jar and classpath management.

This might look like a gargantuan task - and it kind of is - but the benefits of transparent jar version and classpath management are so huge, that I cannot even dare to remember how we did it in my current company before setting up the infrastructure for this.

Also, note that apart from installing ant (with maven-ant-tasks) and maven (with nexus configured) everything else you need to launch is on the SCM.

Answer 2

1. You can add it as an environment variable and then refer to that, if that is feasible.
2. As you already suggested, you can refactor it to a single location.