java.lang.reflect.InvocationTargetExpection

Question

I am having trouble with running Java Applet on site. Applet itself runs localy ok from jar file and there are no errors or warning when compiling it. I even succeselfully signed it, but when I try to run it from website I always get java.lang.reflect.InvocationTargetExpection . Any ideas what I am doing wrong? Heres the applet source code:

    import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import java.io.*; 
public class test {

    private static void createAndShowGUI()  {

        JFrame frame1 = new JFrame("JAVA");
        frame1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

        JButton button = new JButton(" Remote Desktop <<");
        //Add action listener to button
        button.addActionListener(new ActionListener() {

            public void actionPerformed(ActionEvent e)
             { 
                try   {
                Process p = Runtime.getRuntime().exec("C:\\Windows\\System32\\mstsc.exe"); //calls cmd.exe and prints hello world to console
                BufferedReader in = new BufferedReader( 
                new InputStreamReader(p.getInputStream())); 
                String line = null; 
                while ((line = in.readLine()) != null) { 
                System.out.println(line); 
                } 
                } catch (IOException l) { 
                l.printStackTrace(); 
                } 
             }

        });      

        frame1.getContentPane().add(button);
        frame1.pack();
        frame1.setVisible(true);
    }


    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            public void run() {
                createAndShowGUI();
            }
        });
    }
}

And here output from jave console:

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

You need to paste the cause of the InvocationTargetException. Can you show us the full trace? — obataku
– obataku, Commented Aug 26, 2012 at 1:45
This question is unanswerable without a stack trace for the exception. Voting to close ... — Stephen C
– Stephen C, Commented Aug 26, 2012 at 2:59
Do you think it has anything to do with the fact that an applet is trying to run on the host computer C:\\Windows\\System32\\mstsc.exe? — Jon Lin
– Jon Lin, Commented Aug 26, 2012 at 3:22

Aleksander Blomskøld · Accepted Answer · 2012-10-14 18:06:06Z

1

You've compiled your code with JVM version 7, but you're running your applet with an older version of the JVM (for instance 1.6).
You've created a Java Application (with a main method), and not a Applett. To create an Applett your class needs to extend Applett or JApplet.

edited Oct 14, 2012 at 18:06

answered Aug 26, 2012 at 10:39

Aleksander Blomskøld

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1 Comment

Atavius Over a year ago

Well, when I try to run it on machine with JVM 7 applet doesnt work either. I get java.lang.reflect.InvocationTargetException and when I look into console theres nothing. See here slovanet.sk/atavius/test/run.html Any ideas what I am doing wrong?

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