Received error while running java-example image

[Raphael S. Carvalho]

Has anyone a clue on why it happened? Has it something to do with the version of my java?

[raphaelsc@localhost osv]$ sudo scripts/run.py -e "java.so -cp /java-example Hello"
[sudo] password for raphaelsc:
OSv v0.17-12-ge9af4c9
eth0: 192.168.122.15
io.osv.ContextFailedException: java.lang.UnsupportedClassVersionError: Hello : Unsupported major.minor version 52.0
    at io.osv.Context.join(Context.java:63)
    at io.osv.ContextIsolator.runSync(ContextIsolator.java:146)
    at io.osv.RunJava.main(RunJava.java:35)
Caused by: java.lang.UnsupportedClassVersionError: Hello : Unsupported major.minor version 52.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    at io.osv.ContextIsolator.loadClass(ContextIsolator.java:273)
    at io.osv.ContextIsolator.access$300(ContextIsolator.java:32)
    at io.osv.ContextIsolator$3.run(ContextIsolator.java:118)

Regards,

--

Raphael S. Carvalho

[Nadav Har'El]

On Wed, Mar 11, 2015 at 9:24 PM, Raphael S. Carvalho <raph...@cloudius-systems.com> wrote:

Has anyone a clue on why it happened? Has it something to do with the version of my java?

[raphaelsc@localhost osv]$ sudo scripts/run.py -e "java.so -cp /java-example Hello"
[sudo] password for raphaelsc:
OSv v0.17-12-ge9af4c9
eth0: 192.168.122.15
io.osv.ContextFailedException: java.lang.UnsupportedClassVersionError: Hello : Unsupported major.minor version 52.0

Yes indeed: Your java.so is Java 7 (this is the default for our "make image=java") while you compiled Hello.class using Java 8 (this is the default on Fedora 21, for example).

The JRE 7 was not able to run a class file compield with JDK 8's compiler.

You have two options - either use Java 8 on your image ("make image=openjdk8-fedora"), or compile Hello.class for Java 7. Doing the latter is very easy, you can see an example in apps/java-example: basically you need to run "javac -target 7 -source 7 ..." (or if you're not using javac directly, figure out how to do that in however you compile).

You can find the list of Java class major numbers here: http://en.wikipedia.org/wiki/Java_class_file#General_layout

 

    at io.osv.Context.join(Context.java:63)
    at io.osv.ContextIsolator.runSync(ContextIsolator.java:146)
    at io.osv.RunJava.main(RunJava.java:35)
Caused by: java.lang.UnsupportedClassVersionError: Hello : Unsupported major.minor version 52.0
    at java.lang.ClassLoader.defineClass1(Native Method)
    at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
    at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
    at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
    at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
    at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
    at io.osv.ContextIsolator.loadClass(ContextIsolator.java:273)
    at io.osv.ContextIsolator.access$300(ContextIsolator.java:32)
    at io.osv.ContextIsolator$3.run(ContextIsolator.java:118)

Regards,

--

Raphael S. Carvalho

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Nadav Har'El

n...@cloudius-systems.com