JavaFX. Как добавить текст в TextArea из дочернего класса?
Есть проект с использованием фреймворка JavaFX, если свести все к минимально воспроизводимому примеру, то выглядит он так:
Main.java
package main;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class Main extends Application {
@Override
public void start(Stage primaryStage) throws Exception {
Parent root = FXMLLoader.load(getClass().getResource("/fxml/main.fxml"));
primaryStage.setScene(new Scene(root, 600, 400));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
main.fxml
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.TextArea?>
<?import javafx.scene.layout.VBox?>
<VBox maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/19" xmlns:fx="http://javafx.com/fxml/1" fx:controller="main.Controller">
<children>
<TextArea fx:id="textArea" editable="false" prefHeight="406.0" prefWidth="600.0" />
<Button fx:id="button" maxWidth="1.7976931348623157E308" mnemonicParsing="false" onAction="#buttonPressed" prefHeight="26.0" text="Button" />
</children>
</VBox>
Controller.java
package main;
import java.io.IOException;
import javafx.scene.control.Button;
import javafx.scene.control.TextArea;
public class Controller {
public TextArea textArea;
public Button button;
public void buttonPressed() throws IOException {
System.out.println("Button Pressed");
Scan myObj = new Scan();
myObj.run();
}
}
Scan.java
package main;
import java.io.IOException;
public class Scan extends Controller {
public void run() throws IOException {
System.out.println("Scan...");
this.textArea.appendText("Append text to TextArea" + "\n");
}
}
При нажатии на кнопку с fx:id
button
вызывается действие buttonPressed
, в котором создается экземпляр класса Scan
(наследуется от Controller
) и вызывается метод run
. Он в свою очередь должен добавлять текст в элемент TextArea
с fx:id
textArea
:
this.textArea.appendText("Append text to TextArea" + "\n");
Вроде все логично, только вместо желаемого результата я ловлю InvocationTargetException
...
Что я делаю не так?
UPD: Привожу полную версию исключения, только вот все равно ничего не понятно...Копаюсь в исходниках JavaFX, пытаюсь разобраться...
Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at javafx.fxml@20/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1858)
at javafx.fxml@20/javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1726)
at javafx.base@20/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at javafx.base@20/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:232)
at javafx.base@20/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:189)
at javafx.base@20/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at javafx.base@20/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at javafx.base@20/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at javafx.base@20/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at javafx.base@20/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at javafx.base@20/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at javafx.base@20/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at javafx.base@20/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at javafx.base@20/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.base@20/javafx.event.Event.fireEvent(Event.java:198)
at javafx.graphics@20/javafx.scene.Node.fireEvent(Node.java:8944)
at javafx.controls@20/javafx.scene.control.Button.fire(Button.java:203)
at javafx.controls@20/com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:207)
at javafx.controls@20/com.sun.javafx.scene.control.inputmap.InputMap.handle(InputMap.java:274)
at javafx.base@20/com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:247)
at javafx.base@20/com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
at javafx.base@20/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:232)
at javafx.base@20/com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:189)
at javafx.base@20/com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
at javafx.base@20/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at javafx.base@20/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at javafx.base@20/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at javafx.base@20/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at javafx.base@20/com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at javafx.base@20/com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at javafx.base@20/com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at javafx.base@20/com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.base@20/javafx.event.Event.fireEvent(Event.java:198)
at javafx.graphics@20/javafx.scene.Scene$MouseHandler.process(Scene.java:3980)
at javafx.graphics@20/javafx.scene.Scene.processMouseEvent(Scene.java:1890)
at javafx.graphics@20/javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2704)
at javafx.graphics@20/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:411)
at javafx.graphics@20/com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:301)
at java.base/java.security.AccessController.doPrivileged(AccessController.java:400)
at javafx.graphics@20/com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$2(GlassViewEventHandler.java:450)
at javafx.graphics@20/com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:424)
at javafx.graphics@20/com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:449)
at javafx.graphics@20/com.sun.glass.ui.View.handleMouseEvent(View.java:551)
at javafx.graphics@20/com.sun.glass.ui.View.notifyMouse(View.java:937)
at javafx.graphics@20/com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at javafx.graphics@20/com.sun.glass.ui.win.WinApplication.lambda$runLoop$3(WinApplication.java:185)
at java.base/java.lang.Thread.run(Thread.java:1623)
Caused by: java.lang.reflect.InvocationTargetException
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:116)
at java.base/java.lang.reflect.Method.invoke(Method.java:578)
at com.sun.javafx.reflect.Trampoline.invoke(MethodUtil.java:72)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
at java.base/java.lang.reflect.Method.invoke(Method.java:578)
at javafx.base@20/com.sun.javafx.reflect.MethodUtil.invoke(MethodUtil.java:270)
at javafx.fxml@20/com.sun.javafx.fxml.MethodHelper.invoke(MethodHelper.java:84)
at javafx.fxml@20/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1855)
... 46 more
Caused by: java.lang.NullPointerException: Cannot invoke "javafx.scene.control.TextArea.appendText(String)" because "this.textArea" is null
at MeinPortScanner/main.Scan.run(Scan.java:14)
at MeinPortScanner/main.Controller.buttonPressed(Controller.java:23)
at java.base/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:104)
... 53 more