我只是在学习，所以如果答案已经可以找到，请原谅我。我每天四处张望，但找不到我的问题的答案。
我的主要方法是加载登录页面，一切正常，我可以登录到我的应用程序。
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("/view/login.fxml"));
primaryStage.setTitle("Contact Manager");
primaryStage.setScene(new Scene(root, 600, 600));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
登录名将通过以下方法进行操作，并可以很好地加载下一个视图。
public void login(){
String username = System.getProperty("user.name");
String password = login_password.getText();
if(username != "" && password != ""){
User user = new User();
user = user.getByUsername();
if(user.getPassword().equals(password)){
try {
AnchorPane pane = FXMLLoader.load(getClass().getResource("/view/contact_manager.fxml"));
rootPane.getChildren().setAll(pane);
} catch (IOException e) {
e.printStackTrace();
}
} else {
msgLabel.setText("Incorrect username or password!");
}
} else {
msgLabel.setText("Username and password are required!");
}
}
FXML加载良好。
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Tab?>
<?import javafx.scene.control.TabPane?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.layout.Pane?>
<?import javafx.scene.text.Font?>
<?import javafx.scene.text.Text?>
<AnchorPane fx:id="rootPane" fx:controller="controller.ContactsController" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="600" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.202" xmlns:fx="http://javafx.com/fxml/1">
<children>
<Pane prefHeight="70.0" prefWidth="600.0">
<children>
<Text layoutX="189.0" layoutY="42.0" strokeType="OUTSIDE" strokeWidth="0.0" text="Contacts Manager">
<font>
<Font name="Calibri" size="30.0" />
</font>
</Text>
</children>
</Pane>
<AnchorPane fx:id="applicationPane" layoutY="70.0" prefHeight="530.0" prefWidth="600.0">
<children>
<TabPane prefHeight="530.0" prefWidth="600.0" tabClosingPolicy="UNAVAILABLE">
<tabs>
<Tab fx:id="tab_contacts" text="Contacts">
<AnchorPane prefHeight="484.0" prefWidth="600.0" >
<fx:include source="contactsTab.fxml"/>
</AnchorPane>
</Tab>
<Tab fx:id="tab_profile" text="Profile">
<content>
<AnchorPane minHeight="0.0" minWidth="0.0" prefHeight="180.0" prefWidth="200.0">
<fx:include source="profileTab.fxml" />
</AnchorPane>
</content>
</Tab>
</tabs>
</TabPane>
</children>
</AnchorPane>
</children>
</AnchorPane>
但是在下一个控制器中，当我使用以下方法打印applicationPane时
package controller;
import javafx.fxml.FXML;
import javafx.fxml.FXMLLoader;
import javafx.scene.control.MenuButton;
import javafx.scene.control.MenuItem;
import javafx.scene.layout.AnchorPane;
import javafx.scene.paint.Color;
import java.io.IOException;
public class ContactsController {
@FXML AnchorPane applicationPane;
@FXML MenuButton dropdown_contact_type;
@FXML MenuItem select_person;
@FXML MenuItem select_company;
public void new_contact(){
try {
AnchorPane pane = FXMLLoader.load(getClass().getResource("/view/contact_form.fxml"));
applicationPane.getChildren().setAll(pane);
} catch (IOException e) {
e.printStackTrace();
}
}
当我在contactsTab include中单击按钮时，得到以下错误。
<?xml version="1.0" encoding="UTF-8"?>
<?import javafx.scene.control.Button?>
<?import javafx.scene.control.MenuButton?>
<?import javafx.scene.control.MenuItem?>
<?import javafx.scene.control.TableColumn?>
<?import javafx.scene.control.TableView?>
<?import javafx.scene.control.TextField?>
<?import javafx.scene.layout.Pane?>
<?import javafx.scene.layout.Region?>
<?import javafx.scene.layout.VBox?>
<VBox fx:id="contactsTab" maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="506.0" prefWidth="600.0" xmlns="http://javafx.com/javafx/8.0.172-ea" xmlns:fx="http://javafx.com/fxml/1" fx:controller="controller.ContactsController">
<children>
<Pane prefHeight="53.0" prefWidth="600.0">
<children>
<TextField layoutX="14.0" layoutY="14.0" />
<Button layoutX="173.0" layoutY="14.0" mnemonicParsing="false" text="Find" />
<Button fx:id="new_contact" layoutX="561.0" layoutY="14.0" mnemonicParsing="false" onAction="#new_contact" text="+" />
<MenuButton fx:id="dropdown_contact_type" layoutX="443.0" layoutY="14.0" mnemonicParsing="false" prefHeight="25.0" prefWidth="107.0" text="Select Type:" textFill="#948f8f">
<items>
<MenuItem fx:id="select_person" mnemonicParsing="false" onAction="#select_person" onMenuValidation="#select_person" text="Peron" />
<MenuItem fx:id="select_company" mnemonicParsing="false" onAction="#select_company" onMenuValidation="#select_company" text="Company" />
</items>
</MenuButton>
<Region layoutX="212.0" layoutY="2.0" prefHeight="51.0" prefWidth="231.0" />
</children>
</Pane>
<TableView prefHeight="458.0" prefWidth="600.0">
<columns>
<TableColumn prefWidth="153.0" text="Name" />
<TableColumn prefWidth="147.0" text="E-mail" />
<TableColumn prefWidth="159.0" text="Phone" />
<TableColumn prefWidth="140.0" text="Mobile" />
</columns>
</TableView>
</children>
</VBox>
出现以下错误：
Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1774)
at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1657)
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.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:8411)
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.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$MouseHandler.process(Scene.java:3757)
at javafx.scene.Scene$MouseHandler.access$1500(Scene.java:3485)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1762)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2494)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:394)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$358(GlassViewEventHandler.java:432)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:431)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$152(WinApplication.java:177)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1771)
... 52 more
Caused by: java.lang.NullPointerException
at controller.ContactsController.new_contact(ContactsController.java:25)
... 62 more
如果有人能指出我正确的方向，我将是一个非常快乐的人！
预先感谢