Getting started with gradle and java

I always used ant with Apache Ivy or maven to build java applications, so I thought there has to be something better and easier to build the application instead of using them. So I decided to give gradle a go.

To build a project with gradle is quite simple, and unlike ant and maven, managing dependencies is really easy.

build.gradle

apply plugin: 'java'
apply plugin: 'eclipse'

version = '1.0'

eclipse {
    classpath {
       downloadSources=true
       downloadJavadoc=true
    }
}

repositories {
    mavenCentral()
}

dependencies {
    compile 'log4j:log4j:1.2.17'
    compile 'com.google.guava:guava:18.0'
    compile 'io.netty:netty-all:4.0.23.Final'
    testCompile 'junit:junit:4.11'
}

jar {
    from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
    manifest {
        attributes 'Implementation-Title': '', 'Implementation-Version': version
        attributes 'Main-Class': 'com.matoski.blog.demo.Hello'
    }
}

src/main/java/com/matoski/blog/demo/Hello.java

package com.matoski.blog.demo;

public class Hello {

  public static void main(String[] args) {
    System.out.println("Hello");
  }
}

If you run the build command gradle build it will build the project and create a jar file so we can run it.

# gradle build
:compileJava
:processResources UP-TO-DATE
:classes
:jar
:assemble
:compileTestJava UP-TO-DATE
:processTestResources
:testClasses
:test UP-TO-DATE
:check UP-TO-DATE
:build

BUILD SUCCESSFUL

Total time: 12.48 secs

And now we can run the application easily by running

# java -jar build/libs/hello.jar
Hello

It was really simple to build everything with gradle.