[FIXED] Passing Arguments to classes extending the service class Java

Issue

I was wondering if there was a way to pass arguments the a class extending the Service class from the Javafx concurrent package. I would like ProteinariumThread to take in a String argument like ClusterID seen below:

public class ProteinariumThread extends Service<String>{
    String ClusterID = "q";
    @Override


    protected Task<String> createTask(){

        return new Task<String>() {
            @Override
            protected String call() throws Exception {
                updateMessage("Running Proteinarium");
                System.out.println("Asleep");
                ProteinariumRun.PRun(ClusterID);
                System.out.println("Woke Up");
                String woke = "Woke Up";
                return woke;
            }
        };
    }
}

Currently in order to run this background task I use the following bit of code:

final ProteinariumThread service = new ProteinariumThread();
service.start();

This however does not allow me to take in a String argument. Is there anyway to make it that service.start() is able to take in String arguments so that String variable ClusterID can come from outside of the ProteinariumThread class?

final ProteinariumThread service = new ProteinariumThread();
service.start(ClusterID);

Solution

You just need to give your service class a constructor and/or method which accepts the necessary argument. As services are meant to be reusable, it'd probably be best to allow configuration throughout the service's lifetime by exposing a property:

import javafx.beans.property.SimpleStringProperty;
import javafx.beans.property.StringProperty;
import javafx.concurrent.Service;
import javafx.concurrent.Task;

public class ProteinariumService extends Service<String> {

  private final StringProperty clusterId = new SimpleStringProperty(this, "clusterId");
  public final void setClusterId(String clusterId) { this.clusterId.set(clusterId); }
  public final String getClusterId() { return clusterId.get(); }
  public final StringProperty clusterIdProperty() { return clusterId; }

  public ProteinariumService() {}

  public ProteinariumService(String clusterId) {
    setClusterId(clusterId);
  }

  @Override
  protected Task<String> createTask() {
    return new Task<>() {

        final String clusterId = getClusterId(); // cache configuration

        @Override
        protected String call() throws Exception {
            ...
        }
    };
  }
}

It's important you copy the needed state from the service to the task since the task is executed on a background thread.

Then when you need to change the cluster ID you just do:

// or bind the property to something in the UI (e.g. a TextField)
theService.setClusterId(newClusterId);
theService.start();

If you really want to be able to do that in one line you can always define an overload for start in your service class:

public void start(String clusterId) {
  setClusterId(clusterId):
  start();
}

Answered By - Slaw