java.lang.reflect.InvocationTargetException从TextField获取值时 - Javafx

Question

我是Javafx的新手.我正在通过开发一个简单的应用程序来学习Javafx.我正在尝试从javaFXML中的TextField获取值.我有java.lang.reflect.InvocationTargetException.

Javafx文件.

public class Manoj extends Application {

    @Override
    public void start(Stage stage) throws Exception {
        Parent root = FXMLLoader.load(getClass().getResource("FXMLDocument.fxml"));

        Scene scene = new Scene(root);

        stage.setScene(scene);
        stage.show();
    }
    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }

}

FXMLDocument.fxml

<AnchorPane id="AnchorPane" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="480.0" prefWidth="640.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="manoj.FXMLDocumentController">
    <children>
      <AnchorPane layoutX="142.0" layoutY="36.0" prefHeight="361.0" prefWidth="360.0">
         <children>
            <Label fx:id="result" alignment="CENTER" contentDisplay="CENTER" layoutX="61.0" layoutY="289.0" opacity="0.51" prefHeight="77.0" prefWidth="169.0" text="Result Of Addition">
               <font>
                  <Font size="18.0" />
               </font>
            </Label>
            <Label layoutX="26.0" layoutY="108.0" prefHeight="32.0" prefWidth="90.0" text="Number#1 ">
               <font>
                  <Font size="14.0" />
               </font>
            </Label>
            <Label alignment="TOP_CENTER" contentDisplay="CENTER" text="First Application" textAlignment="CENTER">
               <font>
                  <Font name="Cambria" size="50.0" />
               </font>
            </Label>
            <Label layoutX="26.0" layoutY="155.0" prefHeight="32.0" prefWidth="90.0" text="Number#2">
               <font>
                  <Font size="14.0" />
               </font>
            </Label>
              <Button fx:id="button" alignment="CENTER" contentDisplay="CENTER" layoutX="83.0" layoutY="216.0" onAction="#addNumber" prefHeight="44.0" prefWidth="125.0" text="Add Number">
               <font>
                  <Font name="Cambria" size="14.0" />
               </font>
            </Button>
            <TextField fx:id="textone" layoutX="141.0" layoutY="108.0" prefHeight="32.0" prefWidth="179.0" />
            <TextField fx:id="texttwo" layoutX="141.0" layoutY="155.0" prefHeight="32.0" prefWidth="179.0" />
         </children>
         <padding>
            <Insets bottom="20.0" left="20.0" right="20.0" />
         </padding>
      </AnchorPane>
    </children>
   <padding>
      <Insets top="20.0" />
   </padding>
</AnchorPane>

FXMLDocumentController.java

public class FXMLDocumentController implements Initializable {

    @FXML
    private Label result;
    private TextField textone;

    public FXMLDocumentController() {

    }
    @FXML
    private void addNumber(ActionEvent event) {
        System.out.println("Clicked. !");
        String str = textone.getText();
        result.setText(str);
    }

    @Override
    public void initialize(URL url, ResourceBundle rb) {
        // TODO
    }    

}

我正在使用带有场景构建器的netbeans进行开发.当我运行这个项目并单击Add Number按钮时,我得到了一个例外.

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1768)
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1651)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
    at javafx.event.Event.fireEvent(Event.java:204)
    at javafx.scene.Node.fireEvent(Node.java:8175)
    at javafx.scene.control.Button.fire(Button.java:185)
    at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:182)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:96)
    at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
    at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
    at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
    at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
    at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
    at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
    at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
    at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
    at javafx.event.Event.fireEvent(Event.java:204)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3746)
    at javafx.scene.Scene$MouseHandler.access$1800(Scene.java:3471)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1695)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2486)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:314)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:243)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:345)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:526)
    at com.sun.glass.ui.View.notifyMouse(View.java:898)
    at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
    at com.sun.glass.ui.win.WinApplication.access$300(WinApplication.java:39)
    at com.sun.glass.ui.win.WinApplication$4$1.run(WinApplication.java:112)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.reflect.InvocationTargetException
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
    at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:483)
    at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1763)
    ... 47 more
Caused by: java.lang.NullPointerException
    at manoj.FXMLDocumentController.addNumber(FXMLDocumentController.java:33)
    ... 57 more

请帮我摆脱这个例外.提前致谢.

Answer 1

感谢您的评论Jose Pereda.

只是一个简单的粗心错误.正如何塞·佩雷达所说,我添加了@FXML注释textone并且工作正常.