I'm new to Java and Eclipse (C# developer here). I have a requirement to take an open-source Java application (OpenFire) and modify it to suit our needs.
I downloaded Eclipse Juno, I downloaded OpenFire. But something tells me that OpenFire was written using another IDE because when I try to open it in Eclipse, it complains about the element missing in the build.xml file (I used the "Open from an existing Ant BuildFile" option, which OpenFire has).
What can be the best way to approach this type of situation knowing that open-source can be written using so many tools out there? The goal is not to have to change much of the files just to get it into an IDE.
Any help or direction would help.
The IDE does not make a difference to the project unless there are IDE-specific artifacts like .classpath in the project tree. The build.xml file format is set by Ant, not by any one IDE, so it is extremely unlikely that the IDE is the source of your difficulty.
However, IDE-specific files have no place in the source repository.
Rather than chase down a red herring, look at the error in the build.xml and fix that.
Also, to diagnose if your IDE is mismanaging Ant, use ant from the command line to build your project. You should never depend on the IDE to build your project for you, and never use the IDE to build the project for someone else to use. Always use standard build tools like Ant or Maven or Gradle, and always run them from command line or script to get "official" builds.
If you can run your build that way, you are guaranteed independence of IDE irregularities.