Problem running compiled Java programs.

[sogeking99]

I believe this is because I am using Javac version: 1.7.0_03 and maybe the wrong JRE? I am not sure what to do, how to find what versions I'm using really.


Source Code:


class printTest {
public static void main(String[] args){
System.out.println("Hello, world!");
}
}
And this is the error I get when I try to run it:


Exception in thread "main" java.lang.UnsupportedClassVersionError: printTest :
Unsupported major.minor version 51.0
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java :634)
at java.security.SecureClassLoader.defineClass(Secure ClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader .java:277)
at java.net.URLClassLoader.access$000(URLClassLoader. java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java: 212)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.j ava:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:3 21)
at sun.misc.Launcher$AppClassLoader.loadClass(Launche r.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:2 66)
Could not find the main class: printTest. Program will exit.

EDIT: Sorry this is a mess, is there no code tags?

------------------
(program exited with code: 1)
Press return to continue

[codemaniac]

looks like a java version mess up .
You can check your java version by the below command .


java -version

A similar issue has been reported below .

http://stackoverflow.com/questions/7237536/exception-in-thread-main-java-lang-unsupportedclassversionerror-a-unsupporte

[ofnuts]

Use java --version to see what JRE version you have

There is a parameter to Javac ("-target") to tell it to restrict generated code to some earlier version.

[sogeking99]

Okay, this is the output:


owner@ubuntu:~$ java -version
java version "1.6.0_24"
OpenJDK Runtime Environment (IcedTea6 1.11.4) (6b24-1.11.4-1ubuntu0.12.04.1)
OpenJDK 64-Bit Server VM (build 20.0-b12, mixed mode)
owner@ubuntu:~$

[steeldriver]

if you have multiple versions of the jre or jdk installed, you should be able to use



sudo update-alternatives --config java
sudo update-alternatives --config javac
to view and set the version

[sogeking99]

if you have multiple versions of the jre or jdk installed, you should be able to use



sudo update-alternatives --config java
sudo update-alternatives --config javac
to view and set the version

Thanks, this seems to have solved my problem.