Gradle
https://docs.gradle.org/current/userguide/userguide_single.html
Great official userguide with walk through examples
Configuration
LINK Configuration is a named set of dependencies grouped together as a specific goal.
Source sets
the source files and where they’re located
the compilation classpath, including any required dependencies (via Gradle configurations)
where the compiled class files are placed

sourceSet is a placeholder (for main source set it is default)

Dependencies
Repository => e.g. mavenCentral()
Configuration => e.g. implementation
Module coordinate => '<groupId>:<artifactId>:<version>'
Dependency configurations
Every dependency declared for a Gradle project applies to a specific scope. Many Gradle plugins add pre-defined configurations to your project.

Configuration inheritance and composition
Child configurations inherit the whole set of dependencies declared for any of its superconfigurations.

Under the covers the testImplementation
and implementation
configurations form an inheritance hierarchy by calling the method Configuration.extendsFrom(org.gradle.api.artifacts.Configuration[])
Example
Let’s say you wanted to write a suite of smoke tests. Each smoke test makes a HTTP call to verify a web service endpoint. As the underlying test framework the project already uses JUnit. You can define a new configuration named smokeTest
that extends from the testImplementation
configuration to reuse the existing test framework dependency.
configurations {
smokeTest.extendsFrom testImplementation
}
dependencies {
testImplementation 'junit:junit:4.12'
smokeTest 'org.apache.httpcomponents:httpclient:4.5.5'
}
Configurations have at least 3 different roles:
to declare dependencies
as a consumer, to resolve a set of dependencies to files
as a producer, to expose artifacts and their dependencies for consumption by other projects (such consumable configurations usually represent the variants the producer offers to its consumers)
configurations {
// declare a "configuration" named "someConfiguration"
// it doesn’t tell us how the configuration is meant to be used
someConfiguration
}
dependencies {
// add a project dependency to the "someConfiguration" configuration
someConfiguration project(":lib")
}
configurations {
// declare a configuration that is going to resolve the compile classpath of the application
compileClasspath.extendsFrom(someConfiguration)
// declare a configuration that is going to resolve the runtime classpath of the application
runtimeClasspath.extendsFrom(someConfiguration)
}
Api vs Implementation
api - both a compile and runtime dependency on this artifact
implementation - only a runtime dependency on this artifact
Java plugin

Project layout
src/main/java
src/main/resources
src/test/java
src/test/resources
src/
sourceSet
/java
src/
sourceSet
/resources
Configurations
Gray text — the configuration is deprecated.
Green background — you can declare dependencies against the configuration.
Blue-gray background — the configuration is for consumption by tasks, not for you to declare dependencies.
Light blue background with monospace text — a task.


Java extension
java {
sourceCompatibility = JavaVersion.VERSION_1_8
targetCompatibility = JavaVersion.VERSION_1_8
}
Dependency hell
// investigate test class path
gradle -q dependencyInsight --dependency com.h2database --configuration testRuntimeClasspath
gradle -q dependencyInsight --dependency snakeyaml --configuration compileClasspath
// worked recently
gradle etl-core-app:dependencyInsight --dependency databind
Modules
Great article about which kind of modules can exist in the application. LINK
Visualise modules. Tool_1 Tool_2
subprojects vs allprojects
key difference between "subprojects" and "allprojects" is that "subprojects" only applies the settings to the direct subprojects of the current project, while "allprojects" applies the settings to the current project and all of its subprojects.
Build lifecycle

During the configuration phase, Gradle finds the build script(s) in the root and subproject directories.
When a build script, build.gradle(.kts)
, is found, Gradle configures a Project object.
The purpose of the Project object is to create a collection of Task objects, apply plugins, and retrieve dependencies.
Version catalog
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