Good morning,
I would like to sanction a question that is disturbing me, how do I edit a Label from a Thread using a button?
Whenever I run the code I get an error, but if I run that same code without leaving the Label it works perfectly, generating a System.out.println ("some text"); for example.
I would like an explanation on the subject and a solution for it, grateful.
Follow my class Example:
/*
* To change this license header, choose License Headers in Project Properties.
* To change this template file, choose Tools | Templates
* and open the template in the editor.
*/
package Ajuda;
import java.net.URL;
import java.util.ResourceBundle;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.Initializable;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
/**
* FXML Controller class
*
* @author neto_
*/
public class AjudaController implements Initializable {
@FXML
Label label;
@FXML
private Button botao;
@FXML
void apBotao(ActionEvent event) {
thread.start();
}
Thread thread = new Thread(new Runnable() {
@Override
public void run() {
// do work
label.setText("text");
}
});
/**
* Initializes the controller class.
*/
@Override
public void initialize(URL url, ResourceBundle rb) {
}
}
Here is the example of my FXML:
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.Label?>
<?import javafx.scene.layout.AnchorPane?>
<AnchorPane id="AnchorPane" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.141" xmlns:fx="http://javafx.com/fxml/1" fx:controller="Ajuda.AjudaController">
<children>
<Label fx:id="label" layoutX="286.0" layoutY="192.0" text="Label" />
<Button fx:id="botao" layoutX="274.0" layoutY="144.0" mnemonicParsing="false" onAction="#apBotao" text="Button" />
</children>
</AnchorPane>
Error always accusing:
Exception in thread "Thread-4" java.lang.IllegalStateException: Not on FX application thread; currentThread = Thread-4
at com.sun.javafx.tk.Toolkit.checkFxUserThread(Toolkit.java:279)
at com.sun.javafx.tk.quantum.QuantumToolkit.checkFxUserThread(QuantumToolkit.java:423)
at javafx.scene.Parent$2.onProposedChange(Parent.java:367)
at com.sun.javafx.collections.VetoableListDecorator.setAll(VetoableListDecorator.java:113)
at com.sun.javafx.collections.VetoableListDecorator.setAll(VetoableListDecorator.java:108)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.updateChildren(LabeledSkinBase.java:575)
at com.sun.javafx.scene.control.skin.LabeledSkinBase.handleControlPropertyChanged(LabeledSkinBase.java:204)
at com.sun.javafx.scene.control.skin.LabelSkin.handleControlPropertyChanged(LabelSkin.java:49)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase.lambda$registerChangeListener$61(BehaviorSkinBase.java:197)
at com.sun.javafx.scene.control.MultiplePropertyChangeListenerHandler$1.changed(MultiplePropertyChangeListenerHandler.java:55)
at javafx.beans.value.WeakChangeListener.changed(WeakChangeListener.java:89)
at com.sun.javafx.binding.ExpressionHelper$SingleChange.fireValueChangedEvent(ExpressionHelper.java:182)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:81)
at javafx.beans.property.StringPropertyBase.fireValueChangedEvent(StringPropertyBase.java:103)
at javafx.beans.property.StringPropertyBase.markInvalid(StringPropertyBase.java:110)
at javafx.beans.property.StringPropertyBase.set(StringPropertyBase.java:144)
at javafx.beans.property.StringPropertyBase.set(StringPropertyBase.java:49)
at javafx.beans.property.StringProperty.setValue(StringProperty.java:65)
at javafx.scene.control.Labeled.setText(Labeled.java:145)
at Ajuda.AjudaController$1.run(AjudaController.java:38)
at java.lang.Thread.run(Thread.java:748)