Introduction to Gradle

Basic introduction about Gradle

Build automation?

Build automation is the act of scripting or automating a wide variety of tasks that software developers do in their day-to-day activities including things like:

• compiling computer source code into binary code
• packaging binary code
• running automated tests
• deploying to production systems
• creating documentation and/or release notes

Gradle?

• Gradle is a build automation tool that combines Ant's power and flexibility with Maven's build life cycle and dependency management conventions into a more effective way to build.
• Gradle has it's own domain-specific language (DSL) based on Groovy instead of the more traditional XML form of declaring the project configuration.
• Google adopted Gradle as the default build tool for the Android OS. 

Why Gradle? (Gradle v/s Maven v/s Ant)

Build automation tool are consists of two main parts: configuration and build. Configuration is static information about the build such as build scripts and build is dynamic part which actual action happens. * Gradle uses Groovy DSL for it's configuration and Groovy language for customizing it's build. * Maven is focused on configuration, hard to customize. * Ant is focused on build, hard to configure.

Gradle build scripts tend to be much shorter and clearer than those written for Maven or Ant.

• Gradle (build.gradle)

  // build.gradle
  apply plugin: 'java'
  apply plugin: 'checkstyle'
  apply plugin: 'findbugs'
  apply plugin: 'pmd'
  
  
  version = '1.0'
  
  
  repositories {
     mavenCentral()
  }
  
  
  dependencies {
     testCompile group: 'junit', name: 'junit', version: '4.11'
     testCompile group: 'org.hamcrest', name: 'hamcrest-all', version: '1.3'
  }
  

• Maven (pom.xml)

  <!--[pom.xml]-->
  <project xmlns="http://maven.apache.org/POM/4.0.0"
            xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
            xsi:schemaLocation="http://maven.apache.org/POM/4.0.0
            http://maven.apache.org/maven-v4_0_0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.technologyconversations</groupId>
    <artifactId>java-build-tools</artifactId>
    <packaging>jar</packaging>
    <version>1.0</version>
    <dependencies>
       <dependency>
          <groupId>junit</groupId>
          <artifactId>junit</artifactId>
          <version>4.11</version>
       </dependency>
       <dependency>
          <groupId>org.hamcrest</groupId>
          <artifactId>hamcrest-all</artifactId>
          <version>1.3</version>
       </dependency>
    </dependencies>
    <build>
       <plugins>
          <plugin>
             <groupId>org.apache.maven.plugins</groupId>
             <artifactId>maven-compiler-plugin</artifactId>
             <version>2.3.2</version>
          </plugin>
       </plugins>
    </build>
  </project>
  

• Ant (build.xml) with Ivy (ivy.xml)

  <!--[ivy.xml]-->
  <ivy-module version="2.0">
    <info organisation="org.apache" module="java-build-tools"/>
    <dependencies>
       <dependency org="junit" name="junit" rev="4.11"/>
       <dependency org="org.hamcrest" name="hamcrest-all" rev="1.3"/>
    </dependencies>
  </ivy-module>
  
  
  <!--[build.xml]-->
  <project xmlns:ivy="antlib:org.apache.ivy.ant" name="java-build-tools" default="jar">
  
  
    <property name="src.dir" value="src"/>
    <property name="build.dir" value="build"/>
    <property name="classes.dir" value="${build.dir}/classes"/>
    <property name="jar.dir" value="${build.dir}/jar"/>
    <property name="lib.dir" value="lib" />
    <path id="lib.path.id">
       <fileset dir="${lib.dir}" />
    </path>
  
  
    <target name="resolve">
       <ivy:retrieve />
    </target>
  
  
    <target name="clean">
       <delete dir="${build.dir}"/>
    </target>
  
  
    <target name="compile" depends="resolve">
       <mkdir dir="${classes.dir}"/>
       <javac srcdir="${src.dir}" destdir="${classes.dir}" classpathref="lib.path.id"/>
    </target>
  
  
    <target name="jar" depends="compile">
       <mkdir dir="${jar.dir}"/>
       <jar destfile="${jar.dir}/${ant.project.name}.jar" basedir="${classes.dir}"/>
    </target>
  </project>
  

Gradle's compelling features

• Expensive build language and deep API
• Gradle is Groovy
• Flexible conventions
• Robust and powerful dependency management
• Scalable builds
• Effortless extendibility
• Integration with other build tool
• Community-driven and company-backend

How to install Gradle?

• Gradle Installation
  1. Download 'Complete distribution' or 'Binary only distribution' from Gradle Downloads and unpack it.
  2. Create an environment variable GRADLEHOME where your 'gradle-x.x' is located.
  3. Add GRADLEHOME/bin to your PATH environment variable.
  4. Verify if Gradle set up properly with simple command gradle -v.

Gradle is shipped in Android Studio. No external installation is required if you are using Android Studio.

Groovy?

It's hard to discuss Gradle without Groovy language. Groovy is object-oriented programming language and also is a dynamic language and scripting language for JAVA platform. Gradle choose Groovy for it's language because of two main reasons: * The advantages of an internal DSL * Groovy is similar with JAVA * Highest transparency and lowest learning curve especially for developers who are familiar with JAVA

Gradle Wrapper?

Gradle Wrapper is the preferred way of starting a Gradle build. The wrapper is a batch script on Windows, and a shell script for other operating systems. When you start a Gradle build via the wrapper, Gradle will be automatically downloaded and used to run the build.

Author

Name     : Leonardo Taehwan Kim
Email    : contact@thefinestartist.com
Website  : http://www.thefinestartist.com