Java plugin

Java plugin task graph

Compile classes - compileJava, compileTestJava

• JavaCompile Task Class

Manage Resources - processResources, processTestResources

• Copy task Class

Define Dependencies

Package - jar

• Jar Task Class

Run Tests - test

Source Set

Java plugin

It’s gradle core plugin that give you the follow useful features:

• compiling code
• processing resources
• producing a jar file
• running tests

The java plugin initialises project as a java project

It also adds several dependency configuration, which we can declare dependencies against to control the generation of the classpath

Java plugin task graph

build

• assemble
  • jar
    • classes
      • compileJava
      • processResources
• check
  • test
    • classes
      • compileJava
      • processResources
    • testClasses
      • compileTestJava
        • testClasses
          • compileJava
          • processResources
      • processTestResources

Tasks that bolded are task which actually perform an action when they run

The rest of tasks are operate as aggregate tasks

important tasks:

Assemble task

• aggregate task that compileJava, processResources, jar task are depends on this task
• thus then you run this task, it will run all of those tasks sequentially and build a jar file
• assemble and jar task almost the same in that assembling a project without running testing it

Test task

• it’s ensures to run tasks which classes, compileJava, processResources tasks
• besides it also run testClasses, compileTestJava, processTestResources tasks
• that’s ensures that both the main code and test code are built, before running the tests themselves
• test task has dependency on check task
• check and test task almost the same in that testing your code without assembling it

Build task

• top level task of the task graph
• does both assemble and check tasks

if you run the tests without creating the jar file? -> run the check task

if you need to build your project, include creating jar file, without testing your changes? -> run the assemble task

Compile classes - compileJava, compileTestJava

compileJava and compileTestJava are tasks added by java plugin to compile production and test code

These task use whatever java version you’re using to run gradle to compile .java file into .class files

These .class files get output into the build directory

src/main/java/....java -> –> compileJava –> build/classes/java/main/....class

They both type of JavaCompile task class

JavaCompile Task Class

It’s task that compiles java source files, it used by compileJava and compileTestJava task of java plugin

This provides compileOption that many ways to configure the compilation

One of them is setVorbose option which print the compilation verbose

It can configure as follows:

 tasks.named<JavaCompile>("compileJava") {
      options.isVerbose = true
}

if you need to configure both tasks:

tasks.withType<JavaCompile> {
    options.isVerbose = true
}

Like this configuration, we can configure compilation through JavaCompile task class against compileJava and compileTestJava

Manage Resources - processResources, processTestResources

The java plugin’s processResources and processTestResources tasks let us manage resources

When you execute the processResources task, it scans specific directories within your project, and copies their contents into the build directory

src/main/java/resources/hello.txt –> processResources –> build/resources/main/hello.txt

The reason it’s called “processResources” is that it can do additional processing along the way

In fact, these task type of the Copy task class, as in addition to compileJava and compileTestJava tasks they also type of JavaCompile task class

Copy Task Class

To configure processResources and processTestResources task, it should to configure Copy task class

tasks.named<Copy>("processResources") {
    include("**/*.txt")
}

Define Dependencies

The java plugin provides dependency configurations, which determine dependencies are added to the classpath

implementation, compileOnly, runtimeOnly, testImplementation, testCompileOnly, testRuntimeOnly

Package - jar

The java plugin provides a jar task that packages the compiled classes and resources into a single jar file in the build directory

The name of jar file is projectName-projectVersion.jar by default, using the project version in the build script

jar –> build/libs/projectName-projectVersion.jar

Jar Task Class

Like that compileJava and processResources, jar task of java plugin is type of Jar task class

Jar task class can configure related project metadata

Run Tests - test

To run easily your test, the java plugin provides a test task that compiles your test code, process any resources, and then run the tests

It also produces a pretty test report in the build directory

The report tells us what’s passed and what’s failed

Source Set

The java plugin also adds a source set to your project

Source set is a structure of directories that gradle uses to compile and package your code

src/main/java is for java source files and packages

src/main/java/resources is for java resources

src/test/java is for test java source files and packages

src/test/resources is for test java resources

Build directory contains all the gradle build outputs(generated classes, processed resources, test reports, jar files)

and importantly doesn’t get committed into version control

build/classes/java/main is for compiled classes

build/resources/main is for processed resources

build/classes/java/test is for compiled test classes

build/resources/test is for processed test resources