Task Properties and Parameters in Gradle

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In Gradle, task properties and parameters allow you to configure and customize tasks in your build scripts. They provide a way to pass values to tasks and influence their behavior. Task properties are predefined properties provided by Gradle, while task parameters are custom properties that you define. In this tutorial, we will explore how to declare and use task properties and parameters in Gradle.

Understanding Task Properties and Parameters

Task properties and parameters are variables that hold values associated with tasks. They can be used to configure and customize task behavior. The main difference between task properties and parameters is that properties are predefined by Gradle, while parameters are custom properties that you define.

Declaring Task Properties and Parameters

1. Task Properties

Task properties are predefined properties that Gradle provides for certain tasks. They are accessed using the dot notation. For example, the `group` and `description` properties can be used to provide additional information about a task:

task compileJava {
    group = 'build'
    description = 'Compiles Java source code'
}

2. Task Parameters

To define custom task parameters, you can use the `ext` property of a task. This allows you to add custom properties to a task and access them during task execution. For example:

task myTask {
    ext.myParam = 'value'

    doLast {
        println "My custom parameter value: ${myParam}"
    }
}

Common Mistakes to Avoid

• Not properly declaring task properties or parameters, resulting in runtime errors
• Using task properties and parameters interchangeably, without understanding their differences
• Not using the correct syntax to access task properties or parameters

Frequently Asked Questions

1. Can I change the value of a task property or parameter during execution?

   No, task properties and parameters are typically set during configuration time and should not be changed during task execution.

2. Can I pass values to a task parameter from the command line?

   Yes, you can pass values to a task parameter from the command line using the `-P` flag. For example, `gradle myTask -PmyParam=value`.

3. Can I define default values for task parameters?

   Yes, you can define default values for task parameters using the `ext` property. For example, `ext.myParam = 'defaultValue'`.

Summary

Task properties and parameters are powerful features in Gradle that allow you to configure and customize tasks. Task properties provide predefined properties for certain tasks, while task parameters allow you to define custom properties. By leveraging task properties and parameters, you can create flexible and configurable build scripts in Gradle.