Gradle plugin demo written with

1. Create an empty android project in android studio.
2. Create a new module, in my case, I name it as gradleSetUpPlugin.
3. Choose File - New - New Module - Android Library - Next, input name gradleSetUpPlugin, choose language as Java, click Finish.
4. Remove useless folders in module gradleSetUpPlugin:

• gradleSetUpPlugin - libs
• gradleSetUpPlugin - src - androidTest
• gradleSetUpPlugin - src - test
• gradleSetUpPlugin - src - java
• gradleSetUpPlugin - src - main - AndroidManifest.xml

5. Update gradleSetUpPlugin - build.gradle file:

apply plugin: 'groovy'
apply plugin: 'maven'

dependencies {
    implementation gradleApi()
    implementation localGroovy()
}

6. Create a new folder under gradleSetUpPlugin - src - main, name it groovy.
7. Create package under gradleSetUpPlugin - src - main - groovy, as I tend to name the package name for my plugin as com.syna.jk, right click on groovy, New - Package, input desired package name 'com.syna.jk'
8. Not sure why I cannot directly create a new groovy class, so I create a new Java class, right click on package com.syna.jk, New - Java Class, input text "HelloWorldPlugin"
9. Right click on class file "HelloWorldPlugin", Refactor - Rename File, change "HelloWorldPlugin.java" to "HelloWorldPlugin.groovy", then click "Refactor".
10. Now I got a groovy class:

package com.syna.jk;

class HelloWorldPlugin {
}

11. Update details, implements Plugin<Project> and override method apply():

package com.syna.jk

import org.gradle.api.Plugin
import org.gradle.api.Project;

class HelloWorldPlugin implements Plugin<Project> {
    @Override
    void apply(Project project) {

    }
}

12. Add a new task inside the apply() method, for demo I create another groovy class to receive a string parameter:

package com.syna.jk

import org.gradle.api.Plugin
import org.gradle.api.Project;

@SuppressWarnings("unused")
class HelloWorldPlugin implements Plugin<Project> {
    @Override
    void apply(Project project) {
        println("This is apply() inside class HelloWorldPlugin")
        project.extensions.create('demoStrParam', ParamHolder)
        def str = project.demoStrParam.str
        println("Receive param as '${str}'")
        project.task('helloWorldDemo', {
            println("${str} from task 'helloWorldDemo' inside class 'HelloWorldPlugin'")
        })
    }
}

package com.syna.jk;

@SuppressWarnings("unused")
class ParamHolder {

    String str

}

13. This step is important:

Define the plugin name:

• Create a new folder under gradleSetUpPlugin - src - main, right click on main, input resources
• Right click on resources, create folder, input META-INF
• Right click on META-INF, create folder, input gradle-plugins
• Create file, xxx.properties, here xxx will be used as plugin name, here I use com.syna.jk.gradleSetUpTasks.properties.
• Inside the file, add a line of code:

implementation-class=com.syna.jk.HelloWorldPlugin

14. Update gradleSetUpPlugin - buld.gradle

apply plugin: 'groovy'
apply plugin: 'maven'

dependencies {
    implementation gradleApi()
    implementation localGroovy()
}

uploadArchives {
    repositories {
        mavenDeployer {
            repository(url: 'http://xxx/repository/GradleTaskPlugin/') {
                authentication(userName: 'yyy', password: 'zzz')
            }
            pom.project {
                //Make sure to update version and execute gradle task to upload lib to Nexus repo manager
                version '2.0.0_beta001'
                artifactId 'public-gradle-task'
                groupId 'com.syna.jk'
                description 'library'
            }
        }
    }
}

15. Upload gradle plugin to maven repository, run gradle task uploadArchives inside module gradleSetUpPlugin
16. Apply this gradle plugin in the target project:

• In target project, project level build.gradle

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        google()
        jcenter()
        maven {url "http://sha2uvp-gog01.synaptics.com:8081/repository/GradleSetUpPlugin/"}
    }
    dependencies {
        //noinspection GradleDependency
        classpath 'com.android.tools.build:gradle:3.6.3'
        classpath 'de.mannodermaus.gradle.plugins:android-junit5:1.6.0.0'
        //noinspection GradleDependency
        classpath 'com.syna.jk:public-gradle-task:1.0.9'
        classpath 'com.syna.jk:gradle-setUp-plugin:2.0.0_beta001'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
        maven {url "http:/xxx/repository/GradleSetUpPlugin/"}
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}

• In target project, module app level build.gradle:

apply plugin: 'com.syna.jk.gradleSetUpTasks'

gradle.projectsEvaluated {
    connectedDebugAndroidTest.finalizedBy helloWorldDemo
}

demoStrParam {
    str = "Hello World"
}

17. In target project, run command ./gradlew connectedDebugAndroidTest

> Task :app:helloWorldDemo
Receive param as 'Hello World'
Hello World from task 'helloWorldDemo' inside class 'HelloWorldPlugin'

18. In target project, the config can be modified:

• Modify the parameter
• Modify the sequence of the executing gradle commands

gradle.projectsEvaluated {
    connectedDebugAndroidTest.dependsOn helloWorldDemo
}

demoStrParam {
    str = "Hello Groovy"
}

Now the gradle plugin can be successfully imported and applied.