如何在JavaFX中使用控制器动态更新图像

时间：2017-11-26 09:51:17

标签： user-interface javafx nullpointerexception controller scenebuilder

早上好，

我正在尝试创建一个有2个场景的GUI，第一个（GUI）有三个按钮，第二个（NQueensGUI）没有。当第一个场景上的按钮打开第二个窗口时，我想要获取并显示第二个窗口上的图像。我正在尝试创建一个N皇后查看器，我可以在控制台上使用回溯并显示已完成的' N“大小的板，但现在我需要在GUI中进行。我想有一个网格，并填充图像让网格处理大小，因为我将永远有N x N项。无论如何我认为我会有一个非常开始自己的简单示例，但它不起作用。我使用Scenebuilder创建简单的布局。

我有一些代码可以在按下按钮后打开第二个窗口。但后来我得到空指针异常。我想我在通过控制器引用元素时遇到了问题。如果我在程序开始正常时将图像设置为正确，但是当出现问题时它就处于运行状态。到目前为止，这是我的代码，对不起它很乱，但我已经尝试了一切让它工作。

任何人都请告诉我如何正确访问元素，或者我走错了路。

MAIN 

public void start(Stage stage) throws Exception {

    theStage = stage;
    FXMLLoader fxmlLoader = new FXMLLoader();
    fxmlLoader.setLocation(Main.class.getResource("GUI.fxml"));
    Parent root = fxmlLoader.load();
    scene = new Scene(root, 600, 400);
    theStage.setTitle("Project");
    theStage.setScene(scene);
    stage.show();

}

CONTROLLER 

import java.io.File;
import java.io.IOException;
import java.net.URL;
import java.util.ResourceBundle;   
import javafx.application.Platform;
import javafx.collections.ObservableList;
import javafx.event.ActionEvent;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.fxml.Initializable;
import javafx.scene.Node;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.Pane;
import javafx.stage.Stage;

public class GUIFXMLController implements Initializable {
    @FXML
    private ImageView image1;
    @FXML
    private Pane pane;
    @FXML
    private Stage theStage;

    @FXML
    private javafx.scene.control.Button NQueensButton;

    @FXML
    private void handleNQueensButtonAction(ActionEvent event) throws IOException {
        Stage theStage;
        Parent root;
        theStage = (Stage) NQueensButton.getScene().getWindow();
        FXMLLoader fxmlLoader2 = new FXMLLoader();

        root = FXMLLoader.load(getClass().getResource("NQueensGUI.fxml"));
        GUIFXMLController controller = fxmlLoader2.getController();

        Scene scene = new Scene(root,600,400);
        //controller. // Tried this way as well with same error
        ObservableList<Node> list = pane.getChildren(); //PROBLEM
        //list.add(image1); PROBLEM
        theStage.setScene(scene);
        theStage.show();

    }

    @FXML
    private javafx.scene.control.Button ExitButton;

    public void handleExitButtonAction(ActionEvent event) {
        Platform.exit();

    }

    @Override
    public void initialize(URL location, ResourceBundle resources) {

    }

}

NQUEENSGUI 

<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.image.*?>
<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.AnchorPane?>


<Pane fx:id="pane" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="GUIFXMLController">
   <children>
      <ImageView fx:id="image1" fitHeight="150.0" fitWidth="200.0" layoutX="100.0" layoutY="103.0" pickOnBounds="true" preserveRatio="true">
         <image>
            <Image url="queenImageBlack.png" />
         </image>
      </ImageView>
   </children>
</Pane>

GUI 

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.geometry.*?>
<?import javafx.scene.shape.*?>
<?import javafx.scene.image.*?>
<?import javafx.scene.text.*?>
<?import java.lang.*?>
<?import javafx.scene.control.*?>
<?import javafx.scene.layout.*?>
<?import javafx.scene.layout.AnchorPane?>


<Pane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="GUIFXMLController">
   <children>
      <Button fx:id="NQueensButton" layoutX="77.0" layoutY="180.0" mnemonicParsing="false" onAction="#handleNQueensButtonAction" text="N Queens" />
      <Button layoutX="428.0" layoutY="180.0" mnemonicParsing="false" text="Tic Tac Toe" />
      <Button fx:id="ExitButton" layoutX="271.0" layoutY="180.0" mnemonicParsing="false" onAction="#handleExitButtonAction" text="Exit" />
   </children>
</Pane>

错误

 Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1762)
    at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1645)
    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:198)
    at javafx.scene.Node.fireEvent(Node.java:8216)
    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:198)
    at javafx.scene.Scene$MouseHandler.process(Scene.java:3724)
    at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3452)
    at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1728)
    at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2461)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:348)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:273)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:382)
    at com.sun.glass.ui.View.handleMouseEvent(View.java:553)
    at com.sun.glass.ui.View.notifyMouse(View.java:925)
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:1757)
    ... 43 more
Caused by: java.lang.NullPointerException
    at GUIFXMLController.handleNQueensButtonAction(GUIFXMLController.java:45)
    ... 53 more

0 个答案:

没有答案
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