Java FXML控制器的非@FXML实例变量变为null
我正在尝试设计一个类(TabPaneController),用于控制向给定TabPane实例添加和删除选项卡。Java FXML控制器的非@FXML实例变量变为null,java,javafx,javafx-8,fxml,Java,Javafx,Javafx 8,Fxml,我正在尝试设计一个类(TabPaneController),用于控制向给定TabPane实例添加和删除选项卡。 这是我的抽象视图课程: public abstract class AbstractView implements TabUser { private Tab tab; private boolean loaded; void load(String tabName, String fxmlPath) { try {
这是我的抽象视图课程:
public abstract class AbstractView implements TabUser {
private Tab tab;
private boolean loaded;
void load(String tabName, String fxmlPath) {
try {
Parent root = FXMLLoader.load(getClass().getResource(fxmlPath));
tab = new Tab(tabName, root);
loaded = true;
}
catch(IOException e) {
System.out.println("Failed to load tab:\n"+e);
}
}
public abstract void load();
@FXML
public abstract void initialize();
public boolean isLoaded() { return loaded; }
@Override
public Tab getTab() { return tab; }
}
以下是仪表板视图类:
public class DashboardView extends AbstractView {
private String fxmlPath = "fxml/dashboard-view.fxml";
private String tabName = "Dashboard";
// becomes null during onButtonClick()
private TabPaneController tabPaneController;
@FXML
private Button btnSearch, btnSettings, btnAbout;
@Override
public void load() {
load(tabName, fxmlPath);
getTab().setClosable(false);
}
@Override
public void initialize() { }
@FXML
private void onButtonClick(ActionEvent event) {
if(event.getSource() == btnSearch)
tabPaneController.openNewTab(AppViews.SEARCH_VIEW);
}
@Override
public void onTabOpened(TabPaneController tabPaneController) {
this.tabPaneController = tabPaneController;
}
}
public class TabPaneController {
private TabPane tabPane;
public TabPaneController() { }
public void setTabPane(TabPane tabPane) {
this.tabPane = tabPane;
}
public void openNewTab(AbstractView targetView) {
if(!targetView.isLoaded())
targetView.load();
Tab targetTab = targetView.getTab();
// avoids occasional addition of duplicate tabs
if(!tabPane.getTabs().contains(targetTab)) {
targetView.onTabOpened(this);
tabPane.getTabs().add(targetTab);
}
tabPane.getSelectionModel().select(targetTab);
}
}
在调用onTabOpened()
期间,会分配选项卡控件。
此方法由唯一活动的TabPaneController实例调用。
但是在调用onButtonClick()
期间,它不知何故再次变为null
[编辑:如果声明为静态,则选项卡PaneController
不会变为空
下面是选项卡控件类:
public class DashboardView extends AbstractView {
private String fxmlPath = "fxml/dashboard-view.fxml";
private String tabName = "Dashboard";
// becomes null during onButtonClick()
private TabPaneController tabPaneController;
@FXML
private Button btnSearch, btnSettings, btnAbout;
@Override
public void load() {
load(tabName, fxmlPath);
getTab().setClosable(false);
}
@Override
public void initialize() { }
@FXML
private void onButtonClick(ActionEvent event) {
if(event.getSource() == btnSearch)
tabPaneController.openNewTab(AppViews.SEARCH_VIEW);
}
@Override
public void onTabOpened(TabPaneController tabPaneController) {
this.tabPaneController = tabPaneController;
}
}
public class TabPaneController {
private TabPane tabPane;
public TabPaneController() { }
public void setTabPane(TabPane tabPane) {
this.tabPane = tabPane;
}
public void openNewTab(AbstractView targetView) {
if(!targetView.isLoaded())
targetView.load();
Tab targetTab = targetView.getTab();
// avoids occasional addition of duplicate tabs
if(!tabPane.getTabs().contains(targetTab)) {
targetView.onTabOpened(this);
tabPane.getTabs().add(targetTab);
}
tabPane.getSelectionModel().select(targetTab);
}
}
如果我单击调用onButtonClick()
方法的btnSearch
,我会得到一个异常:
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$353(GlassViewEventHandler.java:432)
at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:431)
at com.sun.glass.ui.View.handleMouseEvent(View.java:555)
at com.sun.glass.ui.View.notifyMouse(View.java:937)
at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
at com.sun.glass.ui.gtk.GtkApplication.lambda$null$48(GtkApplication.java:139)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)
at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1769)
... 52 more
Caused by: java.lang.NullPointerException
at app.borax.view.DashboardView.onButtonClick(DashboardView.java:41)
... 62 more
现在我的问题是:
- 为什么仪表板视图中的tabPaneController变为空李>
- 如何预防李>
- 设计TabPaneController的更好方法是什么
我只需要一种机制,可以从任何其他选项卡或任何其他控件(如菜单栏等)将任何AbstractView作为选项卡在选项卡窗格中打开
谢谢。请参阅以及链接-问题在于fxmloader::load
创建了控制器的新实例,因此它不再是您调用onTabOpened
的实例。事实上,这就是问题所在。我从AbstractView
中删除了load
方法,并将其放入另一个类中,该类还将fxmloader::getController
值传递给我的TabPaneController
实例。这解决了问题