java lang UnsupportedClassVersionError

Question

When I ran a java program I received this error   Could you please suggest why do we get this error    Exception in thread  main  java lang UnsupportedClassVersionError       GenerateInvoice  Unsupported major minor version 49 0          at java lang ClassLoader defineClass0 Native Method          at java lang ClassLoader defineClass ClassLoader java 539          at java security SecureClassLoader defineClass SecureClassLoader java 123          at java net URLClassLoader defineClass URLClassLoader java 251          at java net URLClassLoader access 100 URLClassLoader java 55          at java net URLClassLoader 1 run URLClassLoader java 194          at java security AccessController doPrivileged Native Method          at java net URLClassLoader findClass URLClassLoader java 187          at java lang ClassLoader loadClass ClassLoader java 289          at sun misc Launcher AppClassLoader loadClass Launcher java 274          at java lang ClassLoader loadClass ClassLoader java 235          at java lang ClassLoader loadClassInternal ClassLoader java 302

User · Answer

This was a fresh linux Mint xfce machine  I have been battling this for a about a week  I m trying to learn Java on Netbeans IDE and so naturally I get the combo file straight from Oracle  Which is a package of the JDK and the Netbeans IDE together in a tar file located here    located http   www oracle com technetwork java javase downloads index html file name JDK 8u25 with NetBeans 8 0 1  after installing them  or so I thought  I would make compile a simple program like  hello world  and that would spit out a jar file that you would be able to run in a terminal  Keep in mind that the program ran in the Netbeans IDE   I would end up with this error  java lang UnsupportedClassVersionError   Even though I ran the file from oracle website I still had the old version of the Java runtime which was not compatible to run my jar file which was compiled with the new java runtime   After messing with stuff that was mostly over my head from setting Paths to editing  bashrc with no remedy    I came across a solution that was easy enough for even me  I have come across something that auto installs java and configures it on your system and it works with the latest 1 8    One of the steps is adding a PPA wasn t sure about this at first but seems ok as it has worked for me    sudo add-apt-repository ppa webupd8team java  sudo apt-get update   sudo apt-get install oracle-java8-installer     domenic domenic-AO532h     java -version java version  1 8 0 25  Java TM  SE Runtime Environment  build 1 8 0 25-b17  Java HotSpot TM  Server VM  build 25 25-b02  mixed mode   I think it also configures the browser java as well   I hope this helps others

User · Answer

The code was most likely compiled with a later JDK  without using cross-compilation options  and is being run on an earlier JRE   While upgrading the JRE is one solution  it would be better to use the cross-compilation options to ensure the code will run on whatever JRE is intended as the minimum version for the app

User · Answer

This class was compiled with a JDK more recent than the one used for execution   The easiest is to install a more recent JRE on the computer where you execute the program  If you think you installed a recent one  check the JAVA HOME and PATH environment variables   Version 49 is java 1 5  That means the class was compiled with  or for  a JDK which is yet old  You probably tried to execute the class with JDK 1 4  You really should use one more recent  1 6 or 1 7  see java version history

User · Answer

Another option is to delete all the classes and rebuild  Having build file is an ideal solution to control whole process like compilation  packaging and deployment  You can also specify source target versions

[java] java.lang.UnsupportedClassVersionError

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