Exception in init method - JavaFX

I get this exception after exporting into a .jar file with eclipse. IntelliJ says the same. But my program is working fine in eclipse.

Exception in thread "main" java.lang.NoClassDefFoundError: javafx/application/Application
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(Unknown Source)
at java.security.SecureClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.defineClass(Unknown Source)
at java.net.URLClassLoader.access$100(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.launcher.LauncherHelper.checkAndLoadMain(Unknown Source)

Caused by: java.lang.ClassNotFoundException: javafx.application.Application
at java.net.URLClassLoader$1.run(Unknown Source)
at java.net.URLClassLoader$1.run(Unknown Source)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
at java.lang.ClassLoader.loadClass(Unknown Source)
... 13 more

What could be the matter of this?

JDK version: 1.7.0_79 Starting: java -jar myapp.jar

After trying it with java -cp jfxrt.jar -jar myapp.jar it gives me the following error:

java -cp jfxrt.jar -jar memo.jar
Exception in thread "JavaFX Application Thread" Exception in thread "main" java.lang.NoClassDefFoundError: org/apache/log4j/Layout
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:348)
    at com.sun.javafx.application.LauncherImpl.lambda$launchApplicationWithArgs$100(LauncherImpl.java:352)
    at com.sun.javafx.application.PlatformImpl.lambda$runAndWait$119(PlatformImpl.java:326)
    at com.sun.javafx.application.PlatformImpl.lambda$null$117(PlatformImpl.java:295)
    at java.security.AccessController.doPrivileged(Native Method)
    at com.sun.javafx.application.PlatformImpl.lambda$runLater$118(PlatformImpl.java:294)
    at com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
    at com.sun.glass.ui.gtk.GtkApplication._runLoop(Native Method)
    at com.sun.glass.ui.gtk.GtkApplication.lambda$null$450(GtkApplication.java:139)
    at java.lang.Thread.run(Thread.java:745)
Caused by: java.lang.ClassNotFoundException: org.apache.log4j.Layout
    at java.net.URLClassLoader.findClass(URLClassLoader.java:381)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
    at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
    ... 11 more
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.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.NullPointerException
    at com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:383)
    at com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
    ... 5 more

回答1:

The javafx.application.Application class is going to be found in a javafx library; in an IDE such as eclipse you generally configure a project to refer to those libraries it needs for compilation and execution. When you put your code into a jar and run it outside the IDE, you need to provide the library to the runtime a different way.

A standard way to do this is to set a classpath which has references to both the application jar and to any libraries it needs; the DOS command to do this would look something like:

set classpath=c:\myProjects\myApplication\myJar.jar;c:\java\libaries\javafx\jfxrt.jar

and then java would have access to the classes in both those jar files

回答2:

Oracle JDK includes JavaFX on the classpath from version 1.8 onwards; if you upgrade your JDK to version 8 or later it should run. I do not recommend building production-level JavaFX applications with versions prior to Java 8 anyway.

If you really do want to use Java 7, consider using the built-in JavaFX deployment tools to build the jar, instead of the vanilla "create executable jar" from eclipse. These will properly build a jar file that includes the FX runtime, if needed. The easiest way to do this in Eclipse is to install e(fx)clipse (an Eclipse plugin); there's a tutorial which includes steps to build the jar file.