What's with all the Java Build tools?

Question

what's the point of using ant, maven, and buildr? won't the using build in eclipse or netbeans work fine? i'm just curious what the purpose and benefit of extended build tools are.

Answer 1

Different features. For example Maven can scan your dependencies and go download them, and their dependencies so you don't have to. For even a medium sized project there may be a very large number of dependencies. I don't think Eclipse can do that.

Answer 2

The problem with building from the IDE, is that there are tons of settings affecting the build. When you use a build tool all the settings a condensed in a more or less readable form into a small set of scripts or configuration files. This allows in the ideal case anybody to execute a build with hardly any manual setup.

Without the build tool it might become next to impossible to even compile your code in let's say a year, because you'll have to reverse engineer all the settings

Answer 3

In all projects, developers will often manually invoke the Build process.but it is not Suitable for large Projects, Where it is very difficult to keep track of what needs to be built, in what sequence and what dependencies there are in the building process.Hence we Use Build Tools for Our Projects.
Build Tools Done varieties of the task in the Application which will do by the Developer in their daily life.
They are
1.Downloading dependencies.
2.Compiling source code into binary code.
3.Packaging that binary code.
4.Running tests.
5.Deployment to production systems.

Answer 4

On top of all the other answers. The primary reason I keep my projects buildable without being forced to use NetBeans or Eclipse is that it makes it so much easier to setup automated (and continuous) builds.

It would be rather complicated (in comparison) to set up a server that somehow starts eclipse, updates the source from the repository, build it all, sends a mail with the result and copies the output to somewhere on a disk where the last 50 builds are stored.

Answer 5

@anonymous,

• Why do you I assume that me, a member of your team, is using an IDE all the time? I might want to build the code on a headless build server, is that ok?
• Would you also deny me the right of using a continuous integration engine?
• May I fetch dependencies from a central repository please? How can I do that?
• Would you tie me to a specific IDE? I can't run Eclipse easily on my very old laptop, but I'll buy a new one.

Maybe I should also uninstall subversion and use patches or just zip folders on a sftp/ftp/Samba share.

Answer 6

If you are a single developer or a very small group, it can seem that a build system is just an overhead. As the number of developers increases though it quickly becomes difficult to track all changes and ensure developers are keeping in sync. A build system reduces the rate of increase of those overheads as your team grows. Consider the issues of building all the code in Eclipse once you have 100+ developers working on the project.

One compelling reason to have a separate build system is to ensure that what has been delivered to your customers is compiled from a specific version of the code checked into your SCM. This eliminates a whole class of "works on my box" issues and in my opinion this benefit is worth the effort on its own in reduced support time. Isolated builds (say on a CI server) also highlight issues in development, e.g. where partial or breaking changes have been committed, so you have a chance to catch issues early.

A build in an IDE builds whatever happens to be on the box, whereas a standalone build system will produce a reproducible build directly from the SCM. Of course this could be done within an IDE, but AFAIK only by invoking something like Ant or Maven to handle all the build steps.

Then of course there are also the direct benefits of build systems. A modular build system reduces copy-paste issues and handles dependency resolution and other build related issues. This should allow developers to focus on delivering code. Of course every new tool introduces its own issues and the learning curve involved can make it seem that a build system is a needless overhead (just Google I hate Maven to get some idea).