Set onlyIf dependency on Gradle plugin task

Question

I've implemented a Gradle plugin in Java. I followed this tutorial.

My plugin class looks as follows:

public class DemoPlugin implements Plugin<Project> {
    @Override
    public void apply(Project project) {
        project.getExtensions().create("DemoSetting", DemoPluginExtension.class);

        project.getTasks().create("demo", DemoTask.class);
    }
}

Currently I am intended to implement the onlyIf feature but unfortunately I did not succeed yet.

My try is the following:

public class DemoPlugin implements Plugin<Project> {
    @Override
    public void apply(Project project) {
        DemoPluginExtension ext = project.getExtensions().create("demoSetting", DemoPluginExtension.class);

        Closure closure = new Closure(this) {
            public Object doCall() {
                return ext.isExecuteTask();
            }
        };

        project.getTasks().create("demoProperties", demoTask.class).onlyIf(closure);
    }
}

The error I am observing is the following:

What went wrong: Execution failed for task ':demo'. Cannot call Task.setOnlyIf(Closure) on task ':demo' after task has started execution.

I would really appreciate if someone could give me a hint for solving the issue.

Answer 1

Finally I solved it using the following code:

public class DemoPlugin implements Plugin<Project> {
    @Override
    public void apply(Project project) {
        DemoPluginExtension ext = project.getExtensions().create("demoSetting", DemoPluginExtension.class);

        project.getTasks().create("demoProperties", demoTask.class).onlyIf(new Closure(this) {
            public Object call(Object arguments) {
                return true;
            }
        });
    }
}

Please note the implementation of the method

public Object call(Object arguments)

instead of

public Object doCall()