The cleanUp() method must be implemented by all tasks to release any resources. This method is called when the last task in the project has finished executing. Not all tasks need to have code in this method. Only those tasks that hold on to some resources for longer than the task execution should implement this method. In our case, we do not have any resources to release, so we provide a blank implementation as shown below:
@Override
public void cleanUp() {
// We have nothing to cleanup.
}
At this point, your code should compile without errors.