问题描述
我正在研究JavaFX项目来管理锻炼。虽然它有一个大的.fxml文件和一个大的MainController类,但它运行良好:
WorkoutsMain.fxml:
<AnchorPane id="AnchorPane" fx:id="anchorPane" prefHeight="900.0" prefWidth="1600.0" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1" fx:controller="workouts.WorkoutsMainController">
<children>
<SplitPane fx:id="splitPane" dividerPositions="0.15" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0">
<items>
<AnchorPane>
<children>
<StackPane fx:id="menuPane" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0"/>
</children>
</AnchorPane>
<AnchorPane>
<children>
<Pane fx:id="statisticsPane" visible="false" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="130.0"/>
<Pane fx:id="workoutsPane" visible="false" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="130.0">
//... other FX elements
</Pane>
<Pane fx:id="calendarPane" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="130.0"/>
<StackPane fx:id="logoPane" onMouseClicked="#setLogo" AnchorPane.bottomAnchor="778.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="0.0"/>
</children>
</AnchorPane>
</items>
</SplitPane>
</children>
</AnchorPane>
WorkoutsMainController.java:
public class WorkoutsMainController implements Initializable,SplitPaneDividerController {
private final DataBase dataBase = new DataBase();
private boolean first = true;
private String logoName;
@FXML
private StackPane logoPane,menuPane;
private final List<Pane> panes = new ArrayList<>();
@FXML
private Pane calendarPane,workoutsPane,statisticsPane;
@FXML
private SplitPane splitPane;
@FXML
private AnchorPane anchorPane;
// methods and functions
@Override
public void initialize(URL url,ResourceBundle rb) {
setLogo();
disableSplitPaneDivider(splitPane,0.1525);
setUpMainMenu();
}
}
MainClass.java:
public class MainClass extends Application {
private Parent anchorPane;
private final String fxml = "WorkoutsMain.fxml";
@Override
public void start(Stage stage) {
try {
anchorPane = FXMLLoader.load(getClass().getResource(fxml));
} catch (IOException ex) {
System.out.println("Error when trying to load " + fxml);
}
Scene scene = new Scene(anchorPane);
stage.setScene(scene);
stage.getIcons().add(new Image(getClass().getResourceAsStream("/calendarIconWhite.png")));
stage.setTitle("THE WORKOUT CALENDAR 1.7.0 by hazazs®");
stage.setResizable(false);
stage.show();
}
public static void main(String[] args) {
launch(args);
}
}
然后我想从WorkoutsMain.fxml中切出一块。我已经在原始的.fxml大文件中更改了一段,如下所示:
来自
<Pane fx:id="workoutsPane" visible="false" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="130.0">
//... other FX elements
</Pane>
到
<fx:include source="Workouts.fxml" fx:id="workoutsPane"/>
然后,我用其自己的Controller类创建了一个新的fxml文件:
Workouts.fxml:
<Pane fx:id="workoutsPane" visible="false" AnchorPane.bottomAnchor="0.0" AnchorPane.leftAnchor="0.0" AnchorPane.rightAnchor="0.0" AnchorPane.topAnchor="130.0" xmlns:fx="http://javafx.com/fxml/1" fx:controller="workouts.WorkoutsController">
// other FX elements
</Pane>
我已经创建了一个适当的WorkoutsController类,并且已经如下更改了WorkoutsMainController:
public class WorkoutsMainController implements Initializable,SplitPaneDividerController {
protected static final DataBase dataBase = new DataBase();
private final WorkoutsController workoutsController = new WorkoutsController();
private boolean first = true;
private String logoName;
@FXML
private StackPane logoPane,statisticsPane;
@FXML
protected static SplitPane splitPane;
@FXML
protected static AnchorPane anchorPane;
// and so on..
但是从现在开始,当我尝试启动我的应用程序时,我得到了异常:
Exception in Application start method
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 com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
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.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Exception in Application start method
at com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:917)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication$159(LauncherImpl.java:182)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.NullPointerException: Root cannot be null
at javafx.scene.Scene.<init>(Scene.java:336)
at javafx.scene.Scene.<init>(Scene.java:194)
at workouts.MainClass.start(MainClass.java:23)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$166(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$179(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$177(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$178(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$152(WinApplication.java:177)
... 1 more
任何建议者,我应该怎么做才能再次进行这项工作?使用一个.fxml和一个Controller可以完美地工作。
谢谢
解决方法
您正在WorkoutsController
中创建一个新的WorkoutsMainController
实例,而不是使用FXMLLoader
为您创建的实例。您创建的实例中带有@FXML
注释的字段都将为null,因此您可能在某处获取了null指针异常。 (您应该在控制台中看到“尝试加载WorkoutsMain.fxml时出错”消息。)因此,anchorPane
方法中的start()
从未初始化,并且在传递null { {1}}对anchorPane
构造函数的引用。
还请注意,您(出于某些未知原因)已将Scene
和splitPane
anchorPane
设为:这样做没有任何意义,并且static
不会初始化静态领域。因此,这些字段在控制器中也为空。
如果您不压缩加载FXML引发的异常,则将能够看到底层异常的实际堆栈跟踪。
解决方法是:
-
不要创建带有
FXMLLoader
注释的字段@FXML
。参见javafx 8 compatibility issues - FXML static fields -
要为由
static
创建的包含的FXML注入实际的控制器实例,请参阅文档中的Nested Controllers。简而言之,由于您的FXMLLoader
具有fx:include
,因此您应该替换fx:id="workoutsPane"
使用
private final WorkoutsController workoutsController = new WorkoutsController();
(并在
@FXML private WorkoutsController workoutsPaneController ;
的其余部分中将所有出现的workoutsController
替换为workoutsPaneController
)。