Java/HTML - InvocationTargetException thrown

Question

I'm writing a status checker, it is a java web-start applet. I can run it on my computer and it will run just fine, however; when I run it on a web page I get the runtime error java.lang.reflect.InvocationTargetException. This is the html file I'm using to run the jar file

<html>
    <head>
        <applet code="StatusCheckerMain" width=380 height=172 archive="Launch.jar">
            <param name="servername"
                    value="Evolution-X"/>
            <param name="ip"
                    value="127.0.0.1"/>
            <param name="port"
                    value="43594"/>
            Java is not installed on your machine or your browser does not allow Java Web-Start Applets to run.<br /><br />Get the latest Java technology at <a href="http://www.java.com/">http://www.Java.com/</a>
        </applet>
    </head>
</html>

And this is my source file

import java.awt.*;
import java.io.*;
import java.net.*;
import javax.swing.*;
/**
 *
 * @author Dan
 */
public class GUIChecker extends JApplet {

    public GUIChecker() { }

    public void init() {
        try {
            java.awt.EventQueue.invokeAndWait(new Runnable() {
                public void run() {
                    initComponents();
                }
            });
        } catch (Exception ex) {
            ex.printStackTrace();
        }
    }
    private String getServerName() {
        if (isActive()) {
            return (getParameter("servername"));
        } else {
            return "Default";
        }
    }
    private String getIP() {
        if (isActive()) {
            return (getParameter("ip"));
        } else {
            return "localhost";
        }
    }
    private int getPort() {
        if (isActive()) {
            return (Integer.parseInt(getParameter("port")));
        } else {
            return 43594;
        }
    }   
    private boolean checkOnline(String ip, int port) throws UnknownHostException, IOException {
        try {
            Socket sock = new Socket(ip, port);
            return sock.isConnected();
        } catch (ConnectException e) {
            return false;
        }
    }
    private String getConnection(String ip, int port) throws UnknownHostException, IOException {
        try {
            Socket sock = new Socket(ip, port);
            return (sock.isConnected() ? "ONLINE" : "OFFLINE");
        } catch (ConnectException e) {
            return ("OFFLINE");
        }
   }
    @SuppressWarnings("unchecked")
    private void initComponents() {

        jScrollPane1 = new JScrollPane();
        jTextArea1 = new JTextArea();
        setVisible(true);
        jTextArea1.setEditable(false);
        jTextArea1.setColumns(20);
        jTextArea1.setRows(5);
        try {
            Font font = new Font("Verdana", Font.BOLD, 12);
            if (checkOnline(getIP(), getPort())) {
                jTextArea1.setForeground(Color.GREEN);
            } else {
                jTextArea1.setForeground(Color.RED);
            }
            jTextArea1.setFont(font);
            jTextArea1.setText(getServerName()+" IP: "+getIP()+" on port: "+getPort()+" is currently: "+getConnection(getIP(), getPort()));
        } catch (IOException e) {
            e.printStackTrace();
        }

        GroupLayout layout = new GroupLayout(getContentPane());
        getContentPane().setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jScrollPane1, GroupLayout.DEFAULT_SIZE, 385, Short.MAX_VALUE)
                .addContainerGap())
            .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addGap(0, 11, Short.MAX_VALUE)
                    .addComponent(jTextArea1, GroupLayout.PREFERRED_SIZE, 383, GroupLayout.PREFERRED_SIZE)
                    .addGap(0, 11, Short.MAX_VALUE)))
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jScrollPane1, GroupLayout.DEFAULT_SIZE, 121, Short.MAX_VALUE)
                .addContainerGap())
            .addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addGap(0, 12, Short.MAX_VALUE)
                    .addComponent(jTextArea1, GroupLayout.PREFERRED_SIZE, 119, GroupLayout.PREFERRED_SIZE)
                    .addGap(0, 12, Short.MAX_VALUE)))
        );
        validate();
    }
    private JScrollPane jScrollPane1;
    private JTextArea jTextArea1;
}

enter image description here There is no error when running it on my desktop, but when I run it on my webpage this is all I get.

Clear classloader cache ... completed.
Trace level set to 5: all ... completed.basic: Added progress listener: sun.plugin.util.ProgressMonitorAdapter@844c3d
basic: Plugin2ClassLoader.addURL parent called for file:/C:/Users/Dan/Desktop/Evolution-X/Evolution-X%20639/Evolution-X%20%20639%20Server/Evolution-X%20639%20Server/Evolution-X%20639%20Server/SocketsTest/TestConnection/bin/
network: Cache entry not found [url: file:/C:/Users/Dan/Desktop/Evolution-X/Evolution-X%20639/Evolution-X%20%20639%20Server/Evolution-X%20639%20Server/Evolution-X%20639%20Server/SocketsTest/TestConnection/bin/, version: null]
network: Cache entry not found [url: file:/C:/Users/Dan/Desktop/Evolution-X/Evolution-X%20639/Evolution-X%20%20639%20Server/Evolution-X%20639%20Server/Evolution-X%20639%20Server/SocketsTest/TestConnection/bin/, version: null]
basic: exception: java.lang.reflect.InvocationTargetException.
java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at com.sun.deploy.uitoolkit.impl.awt.AWTAppletAdapter.runOnEDTAndWait(Unknown Source)
    at com.sun.deploy.uitoolkit.impl.awt.AWTAppletAdapter.instantiateApplet(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager.initAppletAdapter(Unknown Source)
    at sun.plugin2.applet.Plugin2Manager$AppletExecutionRunnable.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.reflect.InvocationTargetException
    at com.sun.deploy.uitoolkit.impl.awt.OldPluginAWTUtil.invokeAndWait(Unknown Source)
    ... 5 more
Caused by: java.lang.ClassCastException: StatusCheckerMain cannot be cast to java.applet.Applet
    at com.sun.deploy.uitoolkit.impl.awt.AWTAppletAdapter$1.run(Unknown Source)
    at java.awt.event.InvocationEvent.dispatch(Unknown Source)
    at java.awt.EventQueue.dispatchEventImpl(Unknown Source)
    at java.awt.EventQueue.access$200(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.awt.EventQueue$3.run(Unknown Source)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.security.ProtectionDomain$1.doIntersectionPrivilege(Unknown Source)
    at java.awt.EventQueue.dispatchEvent(Unknown Source)
    at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
    at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
    at java.awt.EventDispatchThread.run(Unknown Source)
basic: Removed progress listener: sun.plugin.util.ProgressMonitorAdapter@844c3d
security: Reset deny session certificate store
basic: Dialog type is not candidate for embedding

*"it is a java web-start applet."* 'No' twice over. 1) It is a frame. 2) It is being launched by a standard applet element, not by JWS. — Andrew Thompson, Nov 05 '12 at 00:30
`Integer.parseInt(new JApplet().getParameter("port")))` This is pure nonsense! Wherever you got this code from, put it back there and start again. — Andrew Thompson, Nov 05 '12 at 00:31

score 4 · Accepted Answer · edited Jun 20 '20 at 09:12

4

The applet element is for loading classes of type JApplet and Applet, whereas the code is a JFrame.

So start with something like this.

import javax.swing.*;

/*
<applet code=DialerApplet width=250 height=70>
<param name="servername" value="Evolution-X" >
<param name="ip"  value="127.0.0.1" >
<param name="port" value="43594" >
</applet>
*/
public class DialerApplet extends JApplet {
    public void init() {
        JTextArea ta = new JTextArea(20,5);
        add(new JScrollPane(ta));

        String eol = System.getProperty("line.separator");
        StringBuilder sb = new StringBuilder();
        String[] params = {"servername","ip","port"};
        for (String param : params) {
            sb.append( param );
            sb.append( ": " );
            sb.append( getParameter(param) );
            sb.append( eol );
        }
        ta.setText(sb.toString());

        validate();
    }
}

working applet

Update

The important line in the stack trace is:

Caused by: java.lang.ClassCastException: 
    StatusCheckerMain cannot be cast to java.applet.Applet

This is quite strange.

The code as per the question extends applet.
The console output supports that the cache was flushed (removing old classes that may have been stored).
A JApplet extends Applet - so it can be cast.

Make absolutely sure the new Jar is being copied to whatever place the code is being run from. Also try starting a new project and see if you can get the code I posted to launch as an applet on your machine. If not, it indicates a more fundamental problem.

edited Jun 20 '20 at 09:12

Community

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answered Nov 05 '12 at 00:29

Andrew Thompson

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Perhaps it's not a web start applet, however; this is the way it will need to be loaded to serve it's purpose, so where should I go from here? – Dan Nov 05 '12 at 01:44
Forget 'how it should be loaded' and describe 'where it should appear'. Should it be embedded in a web page, or free floating on the desk-top? – Andrew Thompson Nov 05 '12 at 01:47
It needs to be embedded a web page. – Dan Nov 05 '12 at 01:52
OK. And why does it 'need' to be deployed using JWS? – Andrew Thompson Nov 05 '12 at 01:53
It doesn't need to be deployed using JWS, that was simply a misunderstanding on my end. – Dan Nov 05 '12 at 01:56
That's easy, extend `JApplet` instead of JFrame. (Then deal with the next problem..) – Andrew Thompson Nov 05 '12 at 01:58
Okay, I've updated my file now and made an edit to my original post with the new code, however; I still have the InvocationTargetException Runtime Error. – Dan Nov 05 '12 at 02:35
1) Copy/paste the entire stack trace as an edit to the question. Use code formatting. 2) Let me know in a comment when it is there. 3) And to keep it brief, remove that rubbish with setting a PLAF. It is just noise. – Andrew Thompson Nov 05 '12 at 02:37
Alright, the picture is the error I get, and I've removed where I was setting a PLAF. – Dan Nov 05 '12 at 03:03
So when you press `Details` it pops the console with no useful information? This is tricky. Type 'x' then '5' in the console, return to the web page and reload it. – Andrew Thompson Nov 05 '12 at 03:19
Thank you, StatusCheckerMain was the source of the problem, I didn't think that would be it so I didn't add the class to the question, yet it was apparently. – Dan Nov 05 '12 at 04:00

Java/HTML - InvocationTargetException thrown

1 Answers1

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