# Gradle

In **NixOS**, `nix-shell -p gradle` is enough.

A gradle script handle two things:

* projects
* tasks

`gradle -q hello` :

```groovy
// build.gradle

task hello {
   doLast {
      println "tutorialspoint [${project}]"
      println "[${path}]"
      println "[${projectDir}]"
      println "[${buildDir}]"
   }
}

task upper {
   doLast {
       String expString = 'TUTORIALS point'
       println "Original: " + expString
       println "Upper case: " + expString.toUpperCase()
   }
}

// Take note it is plural tasks
tasks.create(name: 'abc') {
    doLast {
        println("*** abc ***")
    }
}
```

**Task phases:**

* configuration phase
* execution phase (doFirst, doLast)

\---------------------------------------------------------------------------------------------------------------

Sample ok `build.gradle` :

```groovy
apply plugin: 'java'

repositories {
   mavenCentral()
   google()
   jcenter()
}

dependencies {
   compile group: 'com.google.protobuf', name: 'protobuf-java', version: '3.12.2'
   compile group: 'com.google.zxing', name: 'core', version: '3.4.0'
   compile group: 'com.google.zxing', name: 'javase', version: '3.4.0'
   compile group: 'net.java.dev.jna', name: 'jna', version: '5.5.0'
   compile group: 'com.goterl.lazycode', name: 'lazysodium-java', version: '4.2.5'
   compile group: 'co.libly', name: 'resource-loader', version: '1.3.7'
   compile group: 'at.favre.lib', name: 'bytes', version: '1.3.0'
}

task AAA {
    println("-- AAA --")
    doLast {
        println("** AAA **")
    }
}

```

```bash
mkdir -p src/main/java
touch src/main/java/App.java
gradle build
```

Without any java source file, `gradle build` won't download the jars.

How to reference a local jar within `build.gradle`:

```groovy
apply plugin: 'java'

repositories {
   mavenCentral()
   google()
   jcenter()

   flatDir {
      dirs rootDir.absolutePath + '/projectA/src/main/java/proto'
   }
}

dependencies {
   compile group: 'com.google.protobuf', name: 'protobuf-java', version: '3.12.2'
   compile group: 'com.google.zxing', name: 'core', version: '3.4.0'
   compile group: 'com.google.zxing', name: 'javase', version: '3.4.0'
   compile group: 'net.java.dev.jna', name: 'jna', version: '5.5.0'
   compile group: 'com.goterl.lazycode', name: 'lazysodium-java', version: '4.2.5'
   compile group: 'co.libly', name: 'resource-loader', version: '1.3.7'
   compile group: 'at.favre.lib', name: 'bytes', version: '1.3.0'

   // either of these 3 works!
   //compile name: 'card_access.proto'
   //compile fileTree(dir: idpass_proto, include: '*.jar')
   implementation files('src/main/java/proto/card_access.proto.jar')
}
```

To create gradle wrapper:

`gradle wrapper --gradle-version 5.6.1`

These two are the same:

```groovy
dependencies {
  /* THIS
  compile group: 'com.google.protobuf', name: 'protobuf-java', version: '3.12.2'
  compile group: 'com.google.zxing', name: 'core', version: '3.4.0'
  compile group: 'com.google.zxing', name: 'javase', version: '3.4.0'
  compile group: 'net.java.dev.jna', name: 'jna', version: '5.5.0'
  compile group: 'com.goterl.lazycode', name: 'lazysodium-java', version: '4.2.5'
  compile group: 'co.libly', name: 'resource-loader', version: '1.3.7'
  compile group: 'at.favre.lib', name: 'bytes', version: '1.3.0'
  */
  
  // or THIS
  implementation 'com.google.protobuf:protobuf-java:3.12.2'
  implementation 'com.google.zxing:core:3.4.0'
  implementation 'com.google.zxing:javase:3.4.0'
  implementation 'net.java.dev.jna:jna:5.5.0'
  implementation 'com.goterl.lazycode:lazysodium-java:4.2.5'
  implementation 'co.libly:resource-loader:1.3.7'
  implementation 'at.favre.lib:bytes:1.3.0'
}
```

**Gradle File API**

```groovy
task copyPoems(type: Copy) {
  from 'text-files'
  into 'build/poems'
}

task copyjar(type: Copy) {
  from 'text-files/test.jpg'
  into 'c:/Users/63927/cooljars'
}

```

**Control Name of Jar in Gradle**

In `build.gradle`

```groovy
task buildjar(type: Jar) {
    archiveBaseName = 'desired-name-here'
}
```

But you have to invoke the task manually such as: `gradle buildjar` for the task to run.

Know, that this can also be controlled in `settings.gradle` as:

```groovy
rootProject.name = 'desired-name-here'
```