B4J Question webapp: Hello world

[eurojam]

Hi all,
I've made my first steps with B4J webapps and I've tried the hello world example on one of our servers and got this error

stef@j100447:~$ java -jar WebAppHelloWorld.jar
main._process_globals (java line: 70)
java.lang.UnsupportedClassVersionError: anywheresoftware/b4j/object/ServerWrappe                                  r : Unsupported major.minor version 51.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClass(ClassLoader.java:643)
        at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:14                                  2)
        at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
        at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
        at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
        at java.security.AccessController.doPrivileged(Native Method)
        at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:323)
        at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
        at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
        at b4j.example.main._process_globals(main.java:70)
        at b4j.example.main.initializeProcessGlobals(main.java:61)
        at b4j.example.main.main(main.java:28)

stef@j100447:~$ java.lang.UnsupportedClassVersionError: anywheresoftware/b4j/object/ServerWrappe   ^C
stef@j100447:~$ java.lang.UnsupportedClassVersionError: anywheresoftware/b4j/object/ServerWrappe
java.lang.UnsupportedClassVersionError:: command not found

I suppose it is a java version problem...?

stef@j100447:~$ java -version
java version "1.6.0_38"
OpenJDK Runtime Environment (IcedTea6 1.13.10) (6b38-1.13.10-0ubuntu0.12.04.1)
OpenJDK 64-Bit Server VM (build 23.25-b01, mixed mode)

any help will be appreciated
thanks

 

[billzhan]

Wrong Java version. You need jdk7+ (java8.40+ for b4j 4.0+ https://www.b4x.com/android/forum/threads/b4j-v4-01-is-available-for-download.61629/)

 

[Erel]

Note that you don't need to install a new version (though you can). It is enough to download the files and copy them to the server: https://www.b4x.com/android/forum/threads/server-run-a-server-on-a-vps.60378/#content