i had java 6, i am now installing java 7 it told me my binary.tree major/minor was version 50, i needed version 51. i got this error as soon as i opened the project file in greenfoot and hit compile

I got the same thing. The actual message was in a new Window with Java icon Title = Compiler Warnings Text = Warnings from last compilation warning: Drive:\Path\Inventory\BinaryTree\DataElement.class: major version 51 is newer than 50, the highest major version supported by this compiler. It is recommended that the compiler be upgraded. warning: Drive:\Path\Inventory\BinaryTree\DataElement.class: major version 51 is newer than 50, the highest major version supported by this compiler. It is recommended that the compiler be upgraded. END OF MESSAGE Of course, I subbed Drive:\Path for the actual drive and path, but that is unimportant.

When i uninstalled all java, then installed jdk 7.0 : the program worked in greenfoot and in desktop the program did not work online. the web page said "your broswer is ignoring applet tag". i had removed the part of java that the browser could use as a plugin. i am having trouble finding a java platform that will fix this. the most recent JRE that i could find fixed the browser problem, but your scenario still does not run in my browser, although other scenarios do. also, it no longer works on my desktop as a jar file, but it still works in greenfoot. at this point i have java 7 sdk and java 6 jre installed. i cant find a java 7 jre

update: i was able to update my (in mozilla firefox it's java console) to 6.0.32 and i still cannot run your program in firefox. maybe there's some combination of PATH settings that can fix t his, if i find a solution i'll let you know

I think it don't depend on the browser or the operating system... I tried it with 'Google Chrome' and 'Internet Explorer' and on three different comps on the desktop... But it just works in Greenfoot on all three computer... And I can't guess, what the problem could be... :(

I'm not sure. My guess is it might be a problem related to java. a problem with a difference between SDK 7 and JRE 6. maybe the features of SDK7 aren't fully implemeneted into JRE6 yet. i'd check the java website for more information about this, and if there's any way to fix it.

mh... I've checked the Java website... But i haven't found a solution... Perhaps can someone from the Greenfoot programming help me?

I already did that! It's not the fold of any java version. There I'm sure...

It's a problem with the Java version. You have classes in a package/subdirectory called BinaryTree. Greenfoot doesn't support packages, so it never recompiles those classes -- but it will use the compiled .class files you've put in there. Those .class files you have in the BinaryTree package have been compiled by Java 7, for Java 7. This means that anyone who runs a Java applet using the Java 6 plugin will be unable to run your scenario. I've checked and the scenario does run on the Greenfoot website if you are using a Java 7 plugin. If you want it to run on Java 6, recompile those BinaryTree classes using Java 6, then re-publish.

Mhh... I think, there is a problem with a Binarytree you want to import. You've written or in some classes. Isn't there missing the path for java? Because I always just imported with this codes: or I just wonder, that it's working in Greenfoot...

@ nccb That surprise me, now. My comp shows me, that Java 7 is installed, but it's not working... But thank you for your help, I'll remove the BinaryTree package.