Gradle custom task option without value

Question

I'm developing a custom gradle task and i'd like to have an option which does act like a flag and doesn't require a value.

I just want to check if it is set

Basically : I can use plugin either gradle my-task or gradle my-task --flag and be able to check if --flag is present or not to define plugin processing.

I cannot find any thing in the official documentation

Answer 1

Custom command line options for tasks are available since Gradle 4.6 via @Option annotation on task property setters. Documentation link: Declaring and Using Command Line Options.

According to the documentation, value-less command line options are supported via boolean properties.

boolean, Boolean, Property<Boolean>

Describes an option with the value true or false. Passing the option on the command line treats the value as true. For example --enabled equates to true. The absence of the option uses the default value of the property.

(Untested) Example:

import org.gradle.api.tasks.options.Option;

public class MyTask extends DefaultTask {
    private boolean flag;

    @Option(option = "flag", description = "Sets the flag")
    public void setFlag(boolean flag) {
        this.flag = flag;
    }

    @Input
    public boolean isFlag() {
        return flag;
    }

    @TaskAction
    public void doWork() {
        if (flag) {
            getLogger().quiet("Flag is present");
        }
    }
}