Red Hat Enterprise下装jdk，javac,java 什么的都正常，但就是没法出来Hello World!,一运行就出现:Exception in thread "main" java.lang.NoClassDefFoundError: Hello
Caused by: java.lang.ClassNotFoundException: Hello
at java.net.URLClassLoader$1.run(URLClassLoader.java:217)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
Could not find the main class: Hello. Program will exit.
这是怎么回事那？求帮助！万分感谢！

你是不是代码写错了，没有找到这个类，Hello