"Hello World" execution error

[Mike Angelastro]

Hi,

I'm just getting started with Java. I'm trying to run a "Hello" program. The code is:

class Hello {
public static void main(String[] args) {
System.out.println("Hello World!") ;
}
}

It compiles OK but when I run it with "java Hello", I get the following error-

Exception in thread "main" java.lang.UnsupportedClassVersionError: Hello <Unsupported major.minor version 49.0> at java.lang.ClassLoader.defineClass0<Native Method>
etc .....

Did I miss something in my java setup?

Thanks,

Mike

[Ernest Friedman-Hill]

Hi Mike,

Welcome to JavaRanch!

You've got multiple versions of Java installed, and the one you're using to compile the program is newer than the one you're using to run it; specifically, the compiler is JDK 1.5, and the runtime is JDK 1.4 or earlier.

Often when you install the Java plug-in for your Web browser, it will stick a copy of java.exe into your WINDOWS folder or someplace else early on your PATH. You have a number of options: uninstalling the plugin and installing a newer version is one; changing your PATH to put the JDK/bin directory first is another.

[Paul Santa Maria]

If you're running on windows, you might want to use something like this "setjava.bat" script:

set JAVA_HOME="C:\Program Files\Java\jdk1.5.0_05"
set CLASSPATH=.;%JAVA_HOME%\lib
PATH=.;%JAVA_HOME%\bin;%PATH%

You could put it in your project directory, or in a global "utilities" directory.

You could use it as follows:

 
  setjava
 
  javac HelloJava.java
 
  java HelloJava
Hello world!

'Hope that helps .. PSM
[ December 04, 2005: Message edited by: Paul Santa Maria ]

[Mike Angelastro]

Hello Paul and Ernest!

With the help of both of you, I was able to figure it out. I had installed an Oracle demo on my machine and it had references to Java in the path. I moved them to the end of the path, after which my simple little app worked fine.

Thanks a bunch,

Mike