简介
我想创建一些Rectangles，但我总是看到一个nullPointerExeption，或者我不能提供任意多的参数。 我不能制作矩形（宽度，高度，x，y，绘画，绘画（笔画））所以我决定使用RectangleBuilder对象。
我是这样做的。
@FXML
public void group() {
// RB.applyTo(r);
for (double i = 0; i < 5; i++) {
pane.getChildren().add(new Group(g));
r.setStroke(Color.BLACK);
r.setY(i * 25 + 80);
r.setX(100.0);
r.setStroke(Color.BLACK);
r.getParent();
RB.y(r.getY());
RB.x(r.getX());
RB.height(r.getHeight());
RB.width(r.getWidth());
RB.stroke(r.getStroke());
RB.fill(r.getFill());
g.getChildren().add(RB.build());
}
}
以下是对象：
@FXML
Pane pane = new Pane();
@FXML
Rectangle r = new Rectangle();
Group g = new Group();
protected RectangleBuilder RB = null;
我真的不知道是否应该使用RB.getX或RB.applyto（r）。
问题
位于：RB.x（r.getX（））：等。
或在RB.applyto（r）;当我删除此行上的注释标记时。
当我尝试获取有关r Rectangle的信息时问题在RB中。 我可以轻松打开程序，但是当我点击按钮并执行操作＆＃34; group＆＃34;它给了我错误：
错误数据
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1456)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:69)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:28)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Node.fireEvent(Node.java:6867)
at javafx.scene.control.Button.fire(Button.java:179)
at com.sun.javafx.scene.control.behavior.ButtonBehavior.mouseReleased(ButtonBehavior.java:193)
at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:336)
at com.sun.javafx.scene.control.skin.SkinBase$4.handle(SkinBase.java:329)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:64)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:217)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:170)
at com.sun.javafx.event.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:38)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:37)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:35)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:92)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:53)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:33)
at javafx.event.Event.fireEvent(Event.java:171)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3369)
at javafx.scene.Scene$MouseHandler.process(Scene.java:3209)
at javafx.scene.Scene$MouseHandler.access$1900(Scene.java:3164)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1582)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2267)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:250)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:173)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:292)
at com.sun.glass.ui.View.handleMouseEvent(View.java:530)
at com.sun.glass.ui.View.notifyMouse(View.java:924)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.access$100(WinApplication.java:17)
at com.sun.glass.ui.win.WinApplication$3$1.run(WinApplication.java:67)
at java.lang.Thread.run(Thread.java:744)
Caused by: java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:75)
at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:606)
at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:279)
at javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1453)
... 44 more
Caused by: java.lang.NullPointerException
at group.FXMLDocumentController.group(FXMLDocumentController.java:45)
... 54 more
我不知道它是否如此重要。
第45行是：
RB.y(r.getY());
答案 0 :(得分：0)
不要使用RectangleBuilder，它已被弃用，将被删除。
你真正的问题是什么？我的意思是，我在你的代码中看到了很多错误。这是一个关于如何在JavaFX中创建矩形并将它们添加到组中的示例：
public class RectangleDemo extends Application {
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage primaryStage) {
Pane pane = new Pane();
Group group = new Group();
for( int i = 0; i < 5; i++) {
Rectangle rectangle = new Rectangle( 100.0, i*25.0 + 80.0, 20.0, 20.0);
rectangle.setStroke(Color.BLACK);
rectangle.setFill(Color.LIGHTGRAY);
group.getChildren().add( rectangle);
}
pane.getChildren().add(group);
primaryStage.setScene(new Scene( pane, 640, 480));
primaryStage.show();
}
}