I’m a C# guy trying to learn Java. I understand the syntax and the basic architecture of the Java platform, and have no problem doing smaller projects myself, but I’d really like to be able to download some open source projects to learn from the work of others. However, I’m running into a stumbling block that I can’t seem to find any information on.
When I download an open source .NET project, I can open the .sln file with visual studio and everything just loads. Sure, there’s occasionally a missing reference or something, but there’s really very little configuration required to get things going. I’m not sensing the same ease of use with Java. I’m using eclipse at the moment, and it feels like for every project I have to create a brand new Eclipse project using “create from existing source”, and almost nothing compiles properly without significant reconfiguration. In the case of web projects, it’s even worse, because Eclipse doesn’t appear to support creating a web project from existing source. I have to create a standard Java project from source, then then apparently modify the project file to include the bindings for the web toolkit stuff to work properly.
Assuming I want to be able to contribute to a project later on, I shouldn’t have to be making such drastic changes to the file structure to get my IDE to a workable state. What am I missing?
The best way to go about this, is to first remove the IDE from the equation. In C# there is only one environment, so the presence of the default IDE is assumed. In Java a default IDE does not exist.
In the end Java is all about java source files and supporting jars. If you figure out what those are, your 99% of the way home. Then you can apply you favorite build system for the set. Some project require a runtime environment, like a webserver to handle the JSP files. If you understand what the basic setup is (as specified by the specification) you can quickly setup your IDE to handle that.
If I get a project with java files and supporting jars, I fire up Eclipse, create a new project, point it to the project’s base directory and Eclipse will automatically detect what it finds and set up the project accordingly.
But projects often come with a build environment included. The trick is to figure out which one:
if a build.xml file is present, it is using ANT. This is a “make” like tool. You can execute “ant” in the directory where the build file is (if you have ANT installed) and it will try to compile. All IDE’s like Eclipse and NetBeans recognize the build.xml file and allow for starting ant from inside the IDE. There is no guarantee the supporting jars will be present.
if a pom.xml file is present, it is using Maven. Maven is also a make like tool, but enforces a much stricter build cycle. Plus (and this probably is its biggest advantage) it automatically downloads supporting jars. If you have Maven installed you will be amazed at what it downloads… just sit tight, it’ll work out in the end. IDE’s usually require a plugin to support pom.xml, but then you automatically have the whole project setup at once.
if a .project file is present, it usually is a Eclipse project
if a nbproject directory is present, it is a NetBeans project
Getting to know a build environment / IDE is more work that trying to setup a project in the one you know. So I always try to get it running in Eclipse. Usually projects are quite simple to get running once you know your IDE.
Having multiple ways of doing things is not always pleasant, but it’s the cost of having an open community. If there is only one IDE it makes things easier, but I like the fact that there are more people trying to figure out what the best way is to get things done.