Task Properties & Configuration
Learn to add properties to custom tasks, configure them, and ensure incremental builds.
Task Properties & Configuration is a free Groovy & Gradle: JVM Automation and Build Engineering lesson on CoddyKit — lesson 3 of 4. You can read the complete lesson below for free — then practise it hands-on in the browser with a built-in code editor and a 24/7 AI tutor. It is part of the Groovy & Gradle: JVM Automation and Build Engineering learning path, one of 4 lessons in the course, and your progress syncs across the web and the CoddyKit app.
What are Task Properties?
Custom Gradle tasks can be made highly flexible by adding properties. These properties act like variables that allow you to configure a task's behavior from your build.gradle script.
Using properties makes your custom tasks reusable and adaptable to different project needs without having to change their core logic.
Defining Simple Properties
To add a property to a custom task, you simply declare a public field within your task class. For basic types like String, int, or boolean, this is straightforward.
For more advanced scenarios, Gradle also offers dedicated Property types, but we'll start with simple declarations.
Custom Task with a Property
Here's a basic custom task defined directly in build.gradle. It has a message property that will be printed when the task runs. Notice the default value set for the property.
import org.gradle.api.DefaultTask
import org.gradle.api.tasks.TaskAction
class MyMessageTask extends DefaultTask {
String message = "Default task message"
@TaskAction
void printMessage() {
println "Task says: ${message}"
}
}
task helloWorld(type: MyMessageTask)
Configuring Task Properties
Once a task property is defined, you can easily set its value from your build.gradle file. This is done within the task's configuration block, which allows you to customize the task instance.
Run the example to see how the default message is overridden.
import org.gradle.api.DefaultTask
import org.gradle.api.tasks.TaskAction
class MyMessageTask extends DefaultTask {
String message = "Default task message"
@TaskAction
void printMessage() {
println "Task says: ${message}"
}
}
task helloWorld(type: MyMessageTask) {
message = "Hello from CoddyKit!"
}
Inputs for Incremental Builds
One of Gradle's most powerful features is incremental builds. This means Gradle can skip tasks if their inputs and outputs haven't changed since the last build, saving a lot of time.
To enable this, you must tell Gradle which properties are considered task inputs. These are properties whose values influence the task's outcome.
Declaring Input Properties
You mark a property as an input using the @Input annotation. Gradle will then track its value. If the value changes between builds, the task will execute. If not, Gradle can mark it as UP-TO-DATE and skip it.
For file or directory inputs, use @InputFile, @InputDirectory, or @InputFiles.
import org.gradle.api.DefaultTask
import org.gradle.api.tasks.Input
import org.gradle.api.tasks.TaskAction
class MyInputTask extends DefaultTask {
@Input
String greeting = "Hola!"
@TaskAction
void greet() {
println "Greeting: ${greeting}"
}
}
task sayHello(type: MyInputTask) {
greeting = "Bonjour!"
}
Outputs for Incremental Builds
Equally important are outputs. These are the files or directories that your task creates or modifies during its execution. Gradle also tracks these to determine if a task is up-to-date.
If a task's inputs haven't changed AND its declared outputs are present and valid, Gradle knows the task doesn't need to run again.
Declaring Output Properties
You use annotations like @OutputFile for a single result file or @OutputDirectory for a directory containing results. These tell Gradle where the task's generated artifacts will be stored.
The task will ensure the parent directory exists before writing the file.
import org.gradle.api.DefaultTask
import org.gradle.api.tasks.Input
import org.gradle.api.tasks.OutputFile
import org.gradle.api.tasks.TaskAction
class MyOutputFileTask extends DefaultTask {
@Input
String content = "Default report content."
@OutputFile
File outputFile = project.file("build/reports/output.txt")
@TaskAction
void generateFile() {
outputFile.parentFile.mkdirs()
outputFile.write(content)
println "Generated: ${outputFile.name}"
}
}
task generateReport(type: MyOutputFileTask) {
content = "Report data for: " + new Date().format("yyyy-MM-dd HH:mm:ss")
}
The Power of Incremental Builds
By correctly declaring both inputs and outputs, you unlock Gradle's powerful incremental build feature. This means your tasks only run when necessary, drastically speeding up build times.
This optimization is crucial for efficient development workflows and robust CI/CD pipelines, ensuring quick feedback and resource savings.
Quick Check on Properties
Imagine you have a custom Gradle task that takes a specific configuration file as an input. Which annotation would you use for the property that defines the path to this single configuration file?
Recap: Task Properties & Incremental Builds
In this lesson, you learned how to add properties to custom tasks, making them configurable and reusable. You also discovered how to mark properties as inputs (e.g., @Input, @InputFile) and outputs (e.g., @OutputFile, @OutputDirectory).
These annotations are key to enabling Gradle's powerful incremental build feature, which significantly speeds up your builds by skipping tasks that are already up-to-date. Keep practicing to master efficient task configuration!
Frequently asked questions
Is the “Task Properties & Configuration” lesson free?
Yes — the full text of “Task Properties & Configuration” is free to read here on the web, and the Groovy & Gradle: JVM Automation and Build Engineering course includes 4 lessons in total. To practise it interactively (a built-in code editor and a 24/7 AI tutor) and unlock the rest of the Groovy & Gradle: JVM Automation and Build Engineering course, upgrade to CoddyKit PRO.
What will I learn in “Task Properties & Configuration”?
Learn to add properties to custom tasks, configure them, and ensure incremental builds. You practise Groovy & Gradle: JVM Automation and Build Engineering with hands-on code you run directly in the browser, and a 24/7 AI tutor answers your questions as you work through the lesson.
Do I need any experience to start Groovy & Gradle: JVM Automation and Build Engineering?
No prior experience is required. Groovy & Gradle: JVM Automation and Build Engineering on CoddyKit is structured for beginners through advanced learners; this is — lesson 3 of 4, so you can start here or from the beginning and move at your own pace.
How long does the “Task Properties & Configuration” lesson take?
Most CoddyKit lessons take about 5–10 minutes. Each one is bite-sized and interactive, so you make steady progress and pick up exactly where you left off across the web and the app.
Can I write and run code in this Groovy & Gradle: JVM Automation and Build Engineering lesson?
Yes. Every Groovy & Gradle: JVM Automation and Build Engineering lesson includes a built-in code editor, so you write and run real code right in your browser and get instant AI feedback — no local setup required.
All lessons in this course
- Defining Custom Tasks
- Task Types & Actions
- Task Properties & Configuration
- Incremental Tasks & Up-to-Date Checks