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Overview of Gradle to Manage Dependencies
4:48In this video, I'll show you how to use a powerful build tool called Gradle to manage the dependencies (libraries) that your project relies on.
After getting a decent grasp of how the
libraries will be using our bundled as jar
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files, let's now turn to how and where
we're going to obtain those libraries.
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And how we'll get them
into the class path.
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Now, we could just do a simple web search
for a specific jar file we want to use,
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download it, then use an IDE option
to add it to the class path.
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If you search for
instructions on how to do this for
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a specific library, the Spring Web
library, for example, you might be
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surprised to find little guidance on where
to manually download this .jar file.
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Even trickier is that if you were
to download a .jar file, and
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successfully add it to the class path,
you might find that the .jar
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file you downloaded depends on yet
another .jar file.
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Now you have to do it all over again.
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And probably not just once,
but likely many more times.
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And if you ever wanted to share
your project with other developers,
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it'd have to go through the same process.
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If that isn't enough, what happens
when you update your application and
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some libraries are left behind
while new libraries are added?
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Because of this,
most developers use special tools for
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managing what are called dependencies.
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Dependencies of a project are libraries
that a project depends on
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in order to function.
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There are a couple big names out
there in dependency management tools,
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namely Maven and Gradle.
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We're going to use Gradle to manage
our dependencies in this course.
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Fortunately this tool is
integrated with IntelliJ, so
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you should be able to use it without
installing Gradle separately.
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Using what's called a Gradle build file,
we'll be able to list
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the names of the libraries that we
want to incorporate into our project.
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Then, with a click of a button, Gradle
will download all of the .jar files for
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the libraries we listed and even
the libraries our listed ones depend on.
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It's much easier, quicker, and more
reliable than the manual download method.
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I don't know about you, but
I'm itching to code a little bit.
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Remember how we plan on building
an animated gif library called gif lib?
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Let's get that project created in
IntelliJ and see Gradle in action.
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To get started let's open IntelliJ and
create a new project.
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I'll choose Create New Project
from the screen that pops up here.
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From the left hand side,
we'll choose Gradle.
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And with Java selected, we'll click Next.
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The GroupId field should be
formatted like a root package name.
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I'll use com.teamtreehouse.
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The ArtifactId should be an identifier or
project name.
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I'll use giflib.
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And then we shall click Next.
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In the next window,
we'll accept all the defaults.
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Notice that the recommended option here
is to use the default Gradle wrapper,
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which means Gradle as a program will
be included as part of our project.
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Click Next and verify the name and
location of your project.
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When you're ready to create it,
click Finish.
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Let's expand our project, and
take a look at what we have.
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Know that within a few moments, you'll
see your project directory expand as
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the Gradle tool is downloaded and
added to our project directory.
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The first file we'll look at,
is the .iml file.
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As you may know, IntelliJ uses .iml
files to manage module settings.
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Though we're seeing,
we won't actually edit this file, so
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I will go ahead and close it.
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The settings.gradle file simply
contains our root project
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name which we had entered as giflib.
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We also will not edit
this file in this course.
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So, I'll go ahead and close that one too.
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The one file we will concern ourselves
with is the build.gradle file,
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this is the file I referenced in
a previous video where we can list our
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projects dependencies and
Gradle will download them for us.
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Let's check out a couple of
things in the build file.
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I'll go ahead and
hide the tip that's come up in IntelliJ.
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At the top, you see the group inversion
we specified when creating the project.
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For now, suffice it to say, that the group
inversion allow repositories such as
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the one we'll be using
to get our dependencies
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to group related libraries together and
track versions.
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Though I'll leave it alone,
you can change this at any time you like.
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The apply plug-in line tells Gradle to
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add pre-defined functionality when
using Gradle to build our project.
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This particular functionality has
been given the short name Java.
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The repository's blog
allows us to define one or
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more locations where Gradle should
look for the libraries we list.
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We'll use one of the largest public
dependency repositories called
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mavenCentral.
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Finally, we see now where we'll actually
list the libraries that we'll need.
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It's called, quite intuitively,
the dependencies block.
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In the next video we'll replace what's
listed and see Gradle in action.
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