JavaFX - Control and Concurrency

Question

I have a sample Hello World JavaFx. I am using Eclipse and eFxclipse plugin. My Eclipse is kepler which is Eclipse 4.3.2 version and Java servion is Jdk1.7-045.

Wh

Answer 1

A Task is designed to interact with the ui on the fx-application thread, to take advantage of that support you should use it as designed :-)

As a general rule, you must not access ui in the call method [*] of the Task. Instead, update one of its properties (message, progress ...) and bind that property to your ui. Sample code:

Task taskWithBinding = new Task() {
    @Override 
    public Boolean call() {    
        final AtomicInteger i = new AtomicInteger(0);
        for( ; i.get() < 20; i.incrementAndGet()) {
            updateMessage("First row\nSecond row " + i);                      
            try {
                Thread.sleep(1000);
            }
            catch (InterruptedException e) {
                return Boolean.FALSE;
            }
        }
        return Boolean.TRUE;               
    }        
};           
btn.textProperty().bind(taskWithBinding.messageProperty());

[*] The one exception is outlined (wrap the access into an runLater) in the other answer. Doing so is technically correct - but then you are by-passing a Task's abilities and could use an arbitrary Runnable ...