java applet error

i'm getting an error when I run my applet.
my error:

Code:

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java.lang.UnsupportedClassVersionError: applet : Unsupported major.minor version 51.0
        at java.lang.ClassLoader.defineClass1(Native Method)
        at java.lang.ClassLoader.defineClassCond(Unknown Source)
        at java.lang.ClassLoader.defineClass(Unknown Source)
        at java.security.SecureClassLoader.defineClass(Unknown Source)
        at sun.plugin2.applet.Applet2ClassLoader.findClass(Unknown Source)
        at sun.plugin2.applet.Plugin2ClassLoader.loadClass0(Unknown Source)
        at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
        at sun.plugin2.applet.Plugin2ClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at sun.plugin2.applet.Plugin2ClassLoader.loadCode(Unknown Source)
        at sun.plugin2.applet.Plugin2Manager.createApplet(Unknown Source)
        at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
        at java.lang.Thread.run(Unknown Source)
Exception: java.lang.UnsupportedClassVersionError: applet : Unsupported major.minor version 51.0

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my source code:

Code:

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import javax.swing.JApplet;
import javax.swing.SwingUtilities;
import javax.swing.JLabel;

public class AppletMain extends JApplet {
    public void init() {
        try {
            SwingUtilities.invokeAndWait(new Runnable() {
                public void run() {
                    JLabel lbl = new JLabel("Hello World");
                    add(lbl);
                }
            });
        } catch (Exception e) {
            System.err.println("createGUI didn't complete successfully");
        }
    }
}

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Quote:

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java.lang.UnsupportedClassVersionError: applet : Unsupported major.minor version 51.0

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This error message arises when you try to run an applet with a Java runtime that is older than the version you compiled with. In this case you used a JDK 1.7.x to compile with, but your runtime is 1.6.* or less.

You can get the compiler to produce byte code that will run on a specified (or later) runtime by using the -target option. See the javac man page. IDEs allow you to control analogous things through something they will often refer to as "project settings" or similar.

I tried compiling it in several different versions, but i'm still getting the same error. is there another reason i'm getting this error?

Quote:

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is there another reason i'm getting this error?

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No, there isn't.

It's possible you're not running the latest compile. Delete the .class file(s) before recompiling.

db

And web browsers can very "helpfully" not realise that your applet has changed. Try testing things with appletviewer. (I haven't checked, but I am assuming this is still part of the jdk.)

it says unsupported version major.minor 51.0.. i'm assuming this is not the JRE or compiler version? I have re-installed my Google JRE but it had no effect on the applet. I'm running JDK 7 and I think my browser is running a JRE version of 6. Might a version conflict between my browser and PC be causing this error?

Quote:

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Might a version conflict between my browser and PC be causing this error?

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Yes, that is exactly what is causing the error.

See reply #2 for what you do about this. (Or check for an updated java runtime and adjust your browser to use it.)

Quote:

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Originally Posted by jobud9

I have re-installed my Google JRE

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What's that?

db

okay well I re-compiled the class files in a java 6 JDK and I am no longer getting this error. but now it the applet freezes up. I have both JRE 6 and 7. would that be the problem

@db
my Google chrome JRE? it's chromium's java plugin.