java - What is the reason for UnsupportedClassVersionError?

Question

java.lang.UnsupportedClassVersionError: Bad version number in .class file
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:676)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:260)
at java.net.URLClassLoader.access$100(URLClassLoader.java:56)
at java.net.URLClassLoader$1.run(URLClassLoader.java:195)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:188)
at java.lang.ClassLoader.loadClass(ClassLoader.java:317)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:280)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at java.lang.ClassLoader.loadClass(ClassLoader.java:252)
at com.exe4j.runtime.LauncherEngine.launch(Unknown Source)
at com.install4j.runtime.MacLauncher.main(Unknown Source)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:592)
at apple.launcher.LaunchRunner.run(LaunchRunner.java:115)
at apple.launcher.LaunchRunner.callMain(LaunchRunner.java:50)
at apple.launcher.JavaApplicationLauncher.launch(JavaApplicationLauncher.java:52)

I don't understand this at all; can anyone explain it simply? Thanks

Answer 1

This error can occur when you compile the code with a newer version of the JDK and try to run it on an older version of the JVM. Is this your own code you're compiling and are you using an IDE (like Eclipse)? Try updating your JRE.