How do I add libraries to my Gradle file?

Question

It's probably very simple, but only to people who know what they are doing. I have a Java program that imports these two:

import org.apache.commons.lang.StringUtils;
import org.apache.commons.lang.exception.ExceptionUtils;

As an aside, I don't want to use the lang3 package but the lang package.

I do not have anything in my Gradle file about these. When I try to build the file, it gives me errors for these two, saying the packages do not exist.

My questions are:

• Do I need to add them as "compile" or as "api"?
• What is the exact syntax? I have lines that look like this: api group: 'commons-httpclient', name: 'commons-httpclient', version: '3.1'
• How do I find the right name (or should I just invent one)? and the version?

Answer 1

Anything your code needs (besides basic JRE classes) is a dependency for your code. Gradle manages these dependencies, usually downloading them from a repository.

First you need to find such a repository. You probably have repositories already configured in your build.gradle , like so:

buildscript {
    repositories {
        mavenCentral()
        // maybe more repositories
    }
}

That means Gradle will try to download dependencies from Maven Central. You can either do a web search for "gradle" and your dependency, or go to repository and search, or check the dependency's homepage .

You'll end up with a dependency name and version like 'org.apache.commons:commons-lang3:3.12.0' . This needs to go in your build.gradle .

Gradle has different dependencies:

• buildscript dependencies provide code that Gradle needs to execute to build your project, eg, a tool to pull in version control system information or generate code

• implementation dependencies are dependencies your code needs to run, like a logging framework or JSON parser or PDF generator

• test dependencies are dependencies needed to run your automated tests, like JUnit

Depending on where you need the dependency, you put it in the buildscript or the dependencies block.

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'org.tmatesoft.svnkit:svnkit:1.9.+'
    }
}

dependencies {
    implementation 'pdfbox:pdfbox:0.7.3'
    testImplementation 'junit:junit:4.+'
}

You don't need to repeat the implementation dependencies for the testImplementation btw, as it inherits them automatically.

You can define your own configurations as need; see the Gradle manual on dependencies , for example if you have different test suites (unit, integration, performance, ...) that need different dependencies.

Answer 2

you'll have to go to their official website and get the implementations then add those to the dependencies(you'll find it at the bottom of the file) in the build.gradle(module) it would look something like -

the $lifecycle_version might be somethiing like 1.2.3 or some version number.

this is what I got (not exactly sure if this is right)-

implementation 'org.apache.commons:commons-lang3:3.12.0'

got from library website in the gradle short tab

in the build.gradle(project), look for maven repo.

Once done, you'll be able to import the respective libraries.