CODEWITHSUNDEEP
javamultithreadingconcurrencyjavafxjavafx-2
user4671628
user4671628

Reputation:

Listen to background thread from UI JavaFX

I have one problem. I am creating JavaFX application for desktop. I have thread in my app that runs in background, let's assume that it is downloading files from the internet.
I have read articles about concurrency in JavaFX. There is special class Task. I have extended my class with Task. But it can only return some value and after that it will shut down.
But I need to have this task running during all app lifetime, and when , for instance file is downloaded, it should post result to the UI thread, to be more precise on controller which in turn update some ui component.
I know that Task has updateProgress method, maybe I can bind it not only to receive integers, but complex Objects.
Or there is other good approach to follow in my case.
Please help with this problem.

Upvotes: 4

Views: 1270

Answers (2)

ItachiUchiha
ItachiUchiha

Reputation: 36742

JavaFX provides you with ScheduledService which can be scheduled for repetitive works. The javadoc says,

The ScheduledService is a Service which will automatically restart itself after a successful execution, and under some conditions will restart even in case of failure.

A very simple example would be :

ScheduledService<Object> service = new ScheduledService<Object>() {
     protected Task<Object> createTask() {
         return new Task<Object>() {
             protected Object call() {
                 // Connect to a Server
                 // Download the object
                 updateProgress(...);
                 return object; // Useful in case you want to return data, else null
             }
         };
     }
 };
 service.setPeriod(Duration.seconds(10)); //Runs every 10 seconds
 //bind the service progress/message properties
 progressBar.progressProperty().bind(service.progressProperty());

There are non-javafx ways to achieve this as well, you can use :

Upvotes: 2

Sergey Grinev
Sergey Grinev

Reputation: 34508

The easiest way here would be to use plain old Thread:

// create new thread at start, e.g. at the end for Application.start() method
new Thread(new Runnable() {
  public void run() {
      while(true) {
           //load my data 
           // once loaded
           // update UI using 
           Platform.runLater(new Runnable() {
               public void run() {
                   // here goes my update on FX UI thread
               }
           });
           // update is done let's look for more data
      }
  }
}).start();

Upvotes: 1

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