We Keep Coding

Why do we need Gradle in Java? [duplicate]

For past 4 years, I have been programming with Eclipse (for Java), and Visual Studio Express (for C#). The IDEs mentioned always seemed to provide every facility a programmer might ask for (related to programming, of course).
Lately I have been hearing about something called "build tools". I heard they're used almost in all kind of real world development. What are they exactly? What problems are they designed to solve? How come I never needed them in past four years? Are they kind of command-line stripped down IDEs?

What are build tools?
Build tools are programs that automate the creation of executable
applications from source code (e.g., .apk for an Android app). Building
incorporates compiling,linking and packaging the code into a usable or
executable form.
Basically build automation is the act of scripting or automating a
wide variety of tasks that software developers do in their day-to-day
activities like:
Downloading dependencies.
Compiling source code into binary code.
Packaging that binary code.
Running tests.
Deployment to production systems.
Why do we use build tools or build automation?
In small projects, developers will often manually invoke the build
process. This is not practical for larger projects, where it is very
hard to keep track of what needs to be built, in what sequence and
what dependencies there are in the building process. Using an
automation tool allows the build process to be more consistent.
Various build tools available(Naming only few):
For java - Ant,Maven,Gradle.
For .NET framework - NAnt
c# - MsBuild.
For further reading you can refer following links:
1.Build automation
2.List of build automation software
Thanks.

Build tools are tools to manage and organize your builds, and are very important in environments where there are many projects, especially if they are inter-connected. They serve to make sure that where various people are working on various projects, they don't break anything. And to make sure that when you make your changes, they don't break anything either.
The reason you have not heard of them before is that you have not been working in a commercial environment before. There is a whole lot of stuff that you have probably not encountered that you will within a commercial environments, especially if you work in software houses.
As others have said, you have been using them, however, you have not had to consider them, because you have probably been working in a different way to the usual commercial way of working.

Build tools are usually run on the command line, either inside an IDE or completely separate from it.
The idea is to separate the work of compiling and packaging your code from creation, debugging, etc.
A build tool can be run on the command or inside an IDE, both triggered by you. They can also be used by continuous integration tools after checking your code out of a repository and onto a clean build machine.
make was an early command tool used in *nix environments for building C/C++.
As a Java developer, the most popular build tools are Ant and Maven. Both can be run in IDEs like IntelliJ or Eclipse or NetBeans. They can also be used by continuous integration tools like Cruise Control or Hudson.

Build tools are generally to transform source code into binaries - it organize source code, set compile flags, manage dependencies... some of them also integrate with running unit test, doing static analysis, a generating documentation.
Eclipse or Visual Studio are also build systems (but more of an IDE), and for visual studio it is the underlying msbuild to parse visual studio project files under the hood.
The origin of all build systems seems like the famous 'make'.
There are build systems for different languages:
C++: make, cmake, premake
Java: ant+ivy, maven, gradle
C#: msbuild
Usually, build systems either using a propriety domain specific language (make, cmake), or xml (ant, maven, msbuild) to specify a build. The current trend is using a real scripting language to write build script, like lua for premake, and groovy for gradle, the advantage of using a scripting is it is much more flexible, and also allows you the to come up with a set of standard APIs(as build DSL).

These are different types of processes by which you can get your builds done.
1. Continuous Integration build: In this mainly developers check-in their code and right after their check-in a build initiates for building of the recent changes so we should know whether the changes done by the developer has worked or not right after the check-in is done. This is preferred for smaller projects or components of the projects. In case where multiple teams are associated with the project or there are a large no. of developers working on the same project this scenario becomes difficult to handle as if there are 'n' no. of check-in’s and the build fails at certain points it becomes highly difficult to trace whether all the breakage has occurred because of one issue or with multiple issues so if the older issues are not addressed properly than it becomes very difficult to trace down the later defects that occurred after that change. The main benefit of these builds is that we get to know whether a particular check-in is successful or not.
2. Gated check-in builds: In this type of check in a build is initiated right after the check in is done keeping the changes in a shelve sets. In this case if the build succeeds than the shelve-set check-in gets committed otherwise it will not be committed to the Team Foundation Server. This gives a slightly better picture from the continuous integration build as only the successful check-in's are allowed to get committed.
3. Nightly builds: This is also referred as Scheduled builds. In this case we schedule the builds to run for a specific time in order to build the changes. All the previous uncommitted changes from the last build are built during this build process. This is practiced when we want to check in multiple times but do not want a build every time we check in our code so we can have a fixed time or period in which we can initiate the build for building of the checked-in code.
The more details about these builds can be found at the below location.
Gated-check in Builds
Continuous Integration Builds
Nightly Builds

Build Process is a Process of compiling your source code for any errors using some build tools and creating builds(which are executable versions of the project). We(mainly developers) do some modifications in the source code and check-in that code for the build process to happen. After the build process it gives two results :
1. Either build PASSES and you get an executable version of your project(Build is ready).
2. It fails and you get certain errors and build is not created.
There are different types of build process like :
1. Nightly Build
2. gated Build
3. Continuous integration build etc.
Build tools help and automates the process of creating builds.
*So in Short Build is a Version of Software in pre-release format used by the Developer or Development team to gain confidence for the final result of their Product by continuously monitoring their Product and solving any issues early during the development process.*

You have been using them - IDE is a build tool. For the command line you can use things like make.
People use command line tools for things like a nightly build - so in the morning with a hangover the programmer has realised that the code that he has been fiddling with with the latest builds of the libraries does not work!

"...it is very hard to keep track of what needs to be built" - Build tools does not help with that all. You need to know what you want to build. (Quoted from Ritesh Gun's answer)
"I heard they're used almost in all kind of real-world development" - For some reason, software developers like to work in large companies. They seem to have more unclear work directives for every individual working there.
"How come I never needed them in past four years". Probably because you are a skilled programmer.
Pseudo, meta. I think build tools do not provide any really real benefit at all. It is just there to add a sense of security arising from bad company practices, lack of direction - bad software architectural leadership leading to bad actual knowledge of the project. You should never have to use build tools(for testing) in your project. To do random testing with a lack of knowledge of the software project does not give any sort of help at all.
You should never ever add something to a project without knowing it's purpose, and how it will work with the other components. Components can be functional separate, but not work together. (This is the responsibility of the software architect I assume).
What if 4-5 components are added into the project. You add a 6th component. Together with the first added component, it might screw up everything. No automatic would help to detect that.
There is no shortcut other than to think think think.
Then there is the auto download from repositories. Why would you ever want to do that? You need to know what you download, what you add to the project. How do you detect changes in versions of the repositories? You need to know. You can't "auto" anything.
What if we were to test bicycles and baby transports blindfolded with a stick and just randomly hit around with it. That seems to be the idea of build tool testing.
I'm sorry there are no shortcut
https://en.wikipedia.org/wiki/Scientific_method
and
https://en.wikipedia.org/wiki/Analysis

Eclipse IDE setup

I am fairly new to Eclipse and have recently setup the IDE using the base installation. I am mostly working on java projects that use a Spring, Maven and of course all the files that come with a website. I installed several plugins to handle color coding for JS, CSS, JSP and tag files. My IDE now slows down quite a bit after about 2 hours of using it. It's really frustrating having to restart it or suffer slow load times when opening or switching files. I want to know what a good base installation of Eclipse that would include things like color coding for basic files used on the web like javascript, css, xml etc...
If these requirements can't be achieved with a default installation, what should I start with as my base and what plugins are some great stable ones to get for what I require?

Less of an answer, more of a comment.
Eclipse has some performance issues, especially with a lot of plugins running. The web tools project in particular has issues where it appears to re-parse XML files on a ridiculous frequency which causes some serious slowdown.
However, it is still my IDE of choice for Java Web/EE applications. Some quick fixes are:
Upgrade to Eclipse 4--there's no reason not to if you're starting out, it is much faster.
Turn off "Automatic building"
Install it on a RAM drive/SSD so your file-hits move more quickly (the RAM drive, as a bonus, starts clean)
Run it with -clean every once in a while and ditch your local file history
Keep a minimum set of files open.
My general problems are when editing JSF/XML files due to the validation running constantly. Turning off automatic building minimized this.
As to Netbeans...
Netbeans I find to be very sluggish when dealing with EE projects and less intuitive. This might just be personal preference, but in my experience Eclipse makes building and dealing with web projects less of a headache. Additionally the UI feels far more sluggish than Eclipse when dealing with anything substantial. It is faster in some areas and slower in others--basically a wash in productivity in my books (the last time I seriously used it was late 2011 so there might be some improvements I'm unaware of).
Also, make sure you're setting up your servers so that you're not rebuilding from scratch and you're taking advantage of native "hot-code replacement" while debugging or JRebel if you want to spend a bit of cash. It really makes a difference. Additionally "JBoss tools" off the marketplace might be of interest. Some of those plugins are rather helpful.
Lastly
I reboot at my coffee breaks--it really isn't that big a deal in my workflow. It might be a bigger deal in yours.

Few suggestions:
disable "automatically build" in "project"'s menu.
use the latest Eclipse
use the latest JDK for launching eclipse (edit eclispe.ini)
configuring the eclipse.ini (see this question for a complete eclipse.ini). Increase the heap values over there.

What's with all the Java Build tools?

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.

Dependency Management: The build tools follow a component model that provides hints on where to look for dependencies. In Eclipse / Netbeans, you have to depend on a JAR and you don't really know if this JAR has been updated or not. With these build tools, they 'know' updates in dependencies (generally because of a good integration with your source control repository), recalculate transitive dependencies and ensure that everything is always built with the latest versions.
Access Control: Java, apart from class level access control, has no higher abstraction. With these build tools you can specify exactly which projects you want to depend on you and control visibility and access at a higher level of granularity.
Custom Control: The Eclipse / Netbeans build always builds JAR files. With custom build mechanisms, you could build your own custom (company-internal) archive with extra metadata information, if you so wish.
Plugins: There are a variety of plugins that come with build tools which can do various things during build. From something basic like generating Javadocs to something more non-trivial like running tests and getting code coverage, static analysis, generation of reports, etc.
Transport: Some build systems also manage transport of archives - from a development system to a deployment or production system. So, you can configure transport routes, schedules and such.
Take a look at some continuous integration servers like CruiseControl or Hudson. Also, the features page of Maven provides some insight into what you want to know.

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.

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).

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

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.

#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.

The build tools allow you to do a build automatically, without human invention, which is essential if you have a code base being able to build many applications (like we do).
We want to be certain that each and everyone of our applications can build correctly after any code base changes. The best way to check that is to let a computer do it automatically using a Continouos integration tool. We just check in code, and the CI server picks up there is a change and rebuilds all modules influenced by that change. If anything breaks the responsible person is mailed directly.
It is extremely handy being able to automate things.

To expand on Jens Schauder's answer, a lot of those build options end up in some sort of .project file. One of the evils of Eclipse is that they store absolute path names in all of it's project files, so you can't copy a project file from one machine to another, which might have its workspace in a different directory.
The strongest reason for me, is automated builds.

IDEs just work on a higher abstraction layer.
NetBeans nativly uses Ant as its underlying build tool and recently can directly open maven projects in NetBeans. Hence, your typical NetBeans project can be compiled with ant and your maven project already is a NetBeans project.
As with every GUI vs CLI discussion, IDEs seem easier for beginners but once you get the idea it becomes cumbersome to do complex things.
Changing the configuration with an IDE means clicking somewhere which is easy for basic things but for complex stuff you need to find the right place to click. Furthermore IDEs seem to hide the importent information. Clicking a button to add a library is easy but you may still not know where the library is, etc.
In contrast, using a CLI isn't easy to start with but becomes quickly easy. It allows to do complex things more easily.
Using Ant or Maven means that every one can choose his/her own IDE to work one the code. Telling someone to install IDE X to compile it is much more overhead than telling "run <build command> in your shell". And of course your can't explain the former to an external tool.
To sum up, the IDE uses a build tool itself. In case of NetBeans Ant (or Maven) is used so you can get all the advantages and disadvantages of those. Eclipse uses its own thing (as far as I know) but also can integrate ant scripts.
As for the build tools themselves Maven is significantly different from Ant. It can download specified dependencies up to the point of downloading a web server to run your project.

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.

Replacing build.xml with Build.java - using Java and the Ant libraries as a build system

I've grown disillusioned with Groovy based alternatives to Ant. AntBuilder doesn't work from within Eclipse, the Groovy plugin for Eclipse is disappointing, and Gradle just isn't ready yet.
The Ant documentation has a section titled "Using Ant Tasks Outside of Ant" which gives a teaser for how to use the Ant libraries from Java code. There's another example here:
http://www.mail-archive.com/dev#ant.apache.org/msg16310.html
In theory it seems simple enough to replace build.xml with Build.java. The Ant documentation hints at some undocumented dependencies that I'll have to discover (undocumented from the point of view of using Ant from within Java).
Given the level of disappointment with Ant scripting, I wonder why this hasn't been done before. Perhaps it has and isn't a good build system.
Has anyone tried writing build files in Java using the Ant libraries?

Our build system is primarily based upon exactly what you describe, and it works very well indeed. We use the Ant tasks (especially the file-manipulation tasks) from custom java programs which assemble the application using auto-discovery of convention-based application module layout.
You may need some glue Ant XML, to do things like compile the build scripts themselves, and to actually invoke the java to perform the build, but it's minor.
Not only is java more readable than Ant, especially when it comes to conditional execution, but it's vastly quicker. Our Ant-based build used to take a minute or so to assemble an EAR, now the java based version takes about 5 seconds.

You had a fine idea. Cliff Click had a similar idea: http://blogs.azulsystems.com/cliff/2008/01/i-hate-makefile.html
If you go through with it I advise you to keep it as simple as possible so your build system doesn't need a [non-trivial] build system itself.

Given that Java is compiled, this is kind of a chicken and egg problem. You need to build your Build.java to build your project.
Ant currently supports inline scripting using BeanShell, Groovy and a bunch of others, that can really help reduce the need for that.
EDIT: In response to Dean's multiple comments, if your build consists strictly of a long proceedure, then indeed you don't need ant's build script. However, the power of the build script is that it ensures that dependencies are only executed once while allowing for mulitiple entry points, something that is far from trivial if you roll your own.
If you don't like the XML format, you are not alone, the author of ANT agrees with you. However, if your view of the build process is something that can be launched from your IDE as its only launch point, I would say that your build needs are quite simple.
EDIT2: I upvoted skaffman's answer because it speaks directly to the question. In the comments we seem to agree that the approach is fine for a procedural build, but would not work for a declarative one, and that you need at least a little ANT xml to get the ball rolling with your Build.java to avoid the chicken and egg problem. That seems to get to the crux of the matter.

An important point seems to have gotten lost here.
Ant is written in Java and what I'm looking for is a better way to use the Ant tasks (APIs in the Ant libraries) than through xml. For the life of me I can't see how using xml to invoke Java would ever be better or easier than using Java to invoke Java.
The one obstacle is that the xml approach is documented whereas the Java approach is not documented so I'll have to download and get familiar with the Ant code.
I held back from posting this question for a couple of weeks because I was sure that someone had done this before and that my google-foo just needed improving. It just seems so obvious to use Java to call the Ant APIs instead of xml that I'm still surprised that there wasn't a parallel Java-based approach developed for Ant as well as the xml approach.
Just because it is obvious doesn't mean that someone has done it before, though.

While I suppose its possible, you would probably be better off with shell scripts then writing a full on java program to simply automate builds.
You would be missing out on one of the key uses for ant, which are the easy-to-specify filesets and easy to read in properties.
I have stuck with ant as Groovy is too close to writing an entire application to just build your real application. Too complicated for the trouble.

While using Ant tasks inside Java programs is fairly easy, I probably would stick to Ant build files if I were you. If you're doing some groovy development, if Eclipse doesn't do what you need, maybe you need to look elsewhere(IntelliJ, NetBeans, etc.).

Is there any IDE Plugins available to scan while coding?

There are tools like Fortify available which can be integrated with IDE to scan the source codes for security vulnerabilities. But what I expect is a plugin for IDE like eclipse, which should check for vulnerabilities while typing the code. (Probably, in case of a Java program, for every semi-colon(;) it should check for the vulnerability). It would be great if the tool recommends a fix on the go. So that the developer can fix the vulnerabilities as such fixing the compilation issues in eclipse. This would really reduce the developers' time a lot, when compared to running a full scan of the code, checking vulnerabilities, fixing those and scanning the entire code base again.
Is there any such product available in the market already? If not, is it a feasible one to develop such thing?

FindBugs can be made to work in a similar manner perhaps, I have set it to run every time I compile a new file and it warns about some interesting potential bugs. The only plugin I know of that runs as you type is Checkstyle so maybe there's a similar plugin that checks for security vulnerabilities?

Cigital.com They have a plugin that works in a 'spell checker' mode. As you type it will high light the vulnerability code. For example SQL injections, XSS and so in. It works very well and does not hog your machines resources like other plugins.

You can also check out Ounce Labs and Coverity...