关于不同意按钮问题

点击不同意按钮会报错，报空指针异常。下面是代码：

@FXML
protected  void  disagree(){
    int x = ThreadLocalRandom.current().nextInt(600);
    int y = ThreadLocalRandom.current().nextInt(400);
    disLoveBtn.setLayoutX(x);
    disLoveBtn.setLayoutY(y);
}

报错：

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.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:8413)	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$MouseHandler.process(Scene.java:3757)	at javafx.scene.Scene$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$MouseEventNotification.run(GlassViewEventHandler.java:381)	at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:295)	at java.security.AccessController.doPrivileged(Native Method)	at com.sun.javafx.tk.quantum.GlassViewEventHandler.lambda$handleMouseEvent$354(GlassViewEventHandler.java:417)	at com.sun.javafx.tk.quantum.QuantumToolkit.runWithoutRenderLock(QuantumToolkit.java:389)	at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:416)	at com.sun.glass.ui.View.handleMouseEvent(View.java:555)	at com.sun.glass.ui.View.notifyMouse(View.java:937)	at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)	at com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)	at java.lang.Thread.run(Thread.java:748)Caused by: java.lang.reflect.InvocationTargetException	at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)	at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)	at java.lang.reflect.Method.invoke(Method.java:498)	at sun.reflect.misc.Trampoline.invoke(MethodUtil.java:71)	at sun.reflect.GeneratedMethodAccessor1.invoke(Unknown Source)	at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)	at java.lang.reflect.Method.invoke(Method.java:498)	at sun.reflect.misc.MethodUtil.invoke(MethodUtil.java:275)	at javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1771)	... 48 moreCaused by: java.lang.NullPointerException	at sample.Controller.disagree(Controller.java:29)	... 58 more