Error trying to run my compiled program in Java

Question

This is my first program, and my first attempt at running it. I am on Ubuntu.

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(SecureClassLoader.java:142)
at java.net.URLClassLoader.defineClass(URLClassLoader.java:277)
at java.net.URLClassLoader.access$000(URLClassLoader.java:73)
at java.net.URLClassLoader$1.run(URLClassLoader.java:212)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:205)
at java.lang.ClassLoader.loadClass(ClassLoader.java:321)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:294)
at java.lang.ClassLoader.loadClass(ClassLoader.java:266)
Could not find the main class: printTest. Program will exit.


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

EDIT: Okay, this is my JRE version: 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:~$

But my javac version is: 1.7.0_03

kosa · Accepted Answer · 2012-09-06 15:42:31Z

2

Exception in thread "main" java.lang.UnsupportedClassVersionError:

You have runtime JVM version different from Compile time JVM version.

Make sure your classpath points to same JVM version as compile time.

answered Sep 6, 2012 at 15:42

kosa

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6 Comments

neil Over a year ago

Is that something to do with the JRE?

Ren Over a year ago

I was just about to post my answer when the one new answer message popped up xD

kosa Over a year ago

Yes, check your classpath and make sure the JAVA_HOME paths are pointing to same JRE. Are you using any IDE?

neil Over a year ago

@Nambari Yes, well I am using Geany.

kosa Over a year ago

I would suggest check JAVA_HOME settings for that IDE. I never worked on it, so I couldn't point you exact location. There may be something related to compiler version setting also, make sure compiler setting also correct.

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Amit Deshpande · Accepted Answer · 2012-09-06 15:43:05Z

0

There is difference between java version on which you are compiling source code and java version on which you are executing source code.

You are compiling in java 7 and executing in lesser version you need to set JAVA_HOME to java7 only.

Here is how to set JAVA_HOME on Ubantu.

answered Sep 6, 2012 at 15:43

Amit Deshpande

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Comments

user2005617 · Accepted Answer · 2013-04-07 16:23:35Z

0

Try writing your program in a IDE. It is much easier because it shows you the errors in your code and you can easily compile it from the same program. Here is the site where you can download a good one http://www.eclipse.org/downloads/packages/eclipse-ide-java-and-dsl-developers/junosr2

answered Apr 7, 2013 at 16:23

user2005617

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