JavaFX timer problem (Intellij & SceneBuilder)

Question

So basically, I have a project and having problem with creating the timer in JavaFX. Here's the link, it wont work in the code playground but at least you'll have better view:

https://code.sololearn.com/cA46A3A22a11

Every video i found, they use timer and timer task. But when i tried to display the timer using the action button "onAction", i always get this error every second:

Exception in thread "Timer-0" java.lang.IllegalStateException: Not on FX application thread; currentThread = Timer-0
at javafx.graphics/com.sun.javafx.tk.Toolkit.checkFxUserThread(Toolkit.java:291)
at javafx.graphics/com.sun.javafx.tk.quantum.QuantumToolkit.checkFxUserThread(QuantumToolkit.java:424)
at javafx.graphics/javafx.scene.Parent$3.onProposedChange(Parent.java:471)
at javafx.base/com.sun.javafx.collections.VetoableListDecorator.setAll(VetoableListDecorator.java:113)
at javafx.base/com.sun.javafx.collections.VetoableListDecorator.setAll(VetoableListDecorator.java:108)
at javafx.controls/javafx.scene.control.skin.LabeledSkinBase.updateChildren(LabeledSkinBase.java:272)
at javafx.controls/javafx.scene.control.skin.LabeledSkinBase.lambda$new$11(LabeledSkinBase.java:220)
at javafx.controls/com.sun.javafx.scene.control.LambdaMultiplePropertyChangeListenerHandler.lambda$new$1(LambdaMultiplePropertyChangeListenerHandler.java:49)
at javafx.base/javafx.beans.value.WeakChangeListener.changed(WeakChangeListener.java:86)
at javafx.base/com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:181)
at javafx.base/com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:80)
at javafx.base/javafx.beans.property

Answer 1

Could you move the code to code bit and link it there, to increase readability

Answer 2

Maybe this helps:
https://stackoverflow.com/questions/26916640/javafx-not-on-fx-application-thread-when-using-timer

And I also think that you should use TimeLine.
https://docs.oracle.com/javafx/2/animations/basics.htm