java.lang.NoClassDefFoundError

[yyyyyc1]

java.lang.NoClassDefFoundError: net/rebeyond/behinder/core/ShellService
at java.lang.Class.getDeclaredMethods0(Native Method)
at java.lang.Class.privateGetDeclaredMethods(Class.java:2701)
at java.lang.Class.getDeclaredMethods(Class.java:1975)
at javafx.fxml.FXMLLoader$ControllerAccessor.addAccessibleMethods(FXMLLoader.java:3508)
at javafx.fxml.FXMLLoader$ControllerAccessor.access$4000(FXMLLoader.java:3340)
at javafx.fxml.FXMLLoader$ControllerAccessor$1.run(FXMLLoader.java:3459)
at javafx.fxml.FXMLLoader$ControllerAccessor$1.run(FXMLLoader.java:3452)
at java.security.AccessController.doPrivileged(Native Method)
at javafx.fxml.FXMLLoader$ControllerAccessor.addAccessibleMembers(FXMLLoader.java:3451)
at javafx.fxml.FXMLLoader$ControllerAccessor.getControllerMethods(FXMLLoader.java:3411)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2565)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2446)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3249)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3210)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3183)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3159)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:3139)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:3132)
at net.rebeyond.behinder.ui.Main.start(Main.java:18)
at com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$8(LauncherImpl.java:863)
at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$7(PlatformImpl.java:326)
at com.sun.javafx.application.PlatformImpl.lambda$null$5(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.application.PlatformImpl.lambda$runLater$6(PlatformImpl.java:294)
at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method)
at com.sun.glass.ui.win.WinApplication.lambda$null$4(WinApplication.java:185)
at java.lang.Thread.run(Thread.java:750)
Caused by: java.lang.ClassNotFoundException: net.rebeyond.behinder.core.ShellService
at java.net.URLClassLoader.findClass(URLClassLoader.java:387)
at java.lang.ClassLoader.loadClass(ClassLoader.java:418)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:355)
at java.lang.ClassLoader.loadClass(ClassLoader.java:351)
... 28 more
运行时报如下错误，希望大佬们帮忙解答一下，感谢！