Java applet functions aren't being accessed by Javascript

Question

I am trying to create a very simple java Applet to try out using Java functions in a web browser. problem is, is that I can't get any sort of functionality from my applet. I've tried dozens of tutorials and answers from within this site, but nothing produces any different result, The browser always says AppName.FunctionName is not a function.

Here is my html...

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4  /strict.dtd">
<html>
<head>
 <meta content="text/html; charset=ISO-8859-1"
 http-equiv="content-type">
<title>Test Applet</title>
</head>
<body onload="test()">
<applet code="TestApplet.class" name="AppTest"
height="350" width="100"></applet>
<script language="Javascript">
function test(){
alert("Attempt 1");
var elem= document.getElementById('AppTest');
alert(elem);
elem.test();
alert("Attempt 2");
document.AppTest.test();
}
</script><br>
</body>
</html>

and here is my Java code...

import javax.swing.JApplet;

public class TestApplet extends JApplet {

    public String sayHi(){
        return "hello";
    }
    public void test(){
        System.out.println("You did it bro");
    }
}

Any ideas why this seems to do nothing? Note: I am testing it using FireFox

EDIT:

So trying to move closer to a working solution, I modified my html as follows

<html>
<head>
  <title>Test Applet</title>
</head>
<body>
<applet code="AppPack.TestApplet.class"
 codebase="TestApplet.jar" name="AppTest"
 scriptable="true" height="350" width="100"></applet>
<script language="Javascript">function test(){
document.AppTest.test();
}
</script><br>
<input name="tryit" value="TryIt" onclick="test()"
 type="button">
</body>
</html>

I've tried to use the codebase declaration, seeing as how including it draws the applet to the canvas, however the box just contains an error saying class not found exception, and without it I get a blank page with just the button. ALL the files are in the same directory, and if I test the applet in eclipse, it generates html to run the applet in the viewer, but these html files also don't load if opened simply using a broswer. Please, can anyone shed some light on what I am doing wrong?

The test function is called too soon. - The applet should not have a constructor. Put that code in the init() and declare it scriptable='true' when deploying. Why code an applet? If it is due to spec. by teacher, please refer them to Why CS teachers should stop teaching Java applets. — Andrew Thompson
– Andrew Thompson, Commented Sep 14, 2013 at 8:01
Can you give me an example of what you mean? And the applet is for a work related project, we want to have access to certain Java utilities on the server side for internal use. — adam5990
– adam5990, Commented Sep 17, 2013 at 14:35
"Can you give me an example of what you mean?" Can you answer my question - namely "Why code an applet?" — Andrew Thompson
– Andrew Thompson, Commented Sep 17, 2013 at 14:38
As I mentioned, we are working on a browser based application for internal use, we want some Java utilities to alter files saved on disk on the server side, the applet is a way for us to access Java from our browser, if there is a better way to access Java classes in html or javascript I'd be interested in learning more. For the purposes of this question however, I am unclear by what you meant when you said " Put that code in the init() and declare it scriptable='true'", can you clarify? — adam5990
– adam5990, Commented Sep 17, 2013 at 14:56
"I am unclear by what you meant when you said " Put that code in the init() and declare it scriptable='true'", can you clarify?" Interestingly, neither of those things are the main problem (AFAIU), that was covered in the first sentence. As to 'unclear' - what are you unclear about? Be specific, since I don't intend to write an applet tutorial in comments.. — Andrew Thompson
– Andrew Thompson, Commented Sep 17, 2013 at 15:28

Andrew Thompson · Accepted Answer · 2013-09-17 16:38:42Z

2

The test function is called too soon.

An applet won't necessarily be loaded and started by the time the page onload function is called. That really only means that the browser has read all the HTML related to the page, not necessarily images, (externally defined) styles or scripts, or things that might be created as a result of the page loading (e.g. the applet).

Put the call to the test() method into a button that you click, wait 'a few moments' after page load, and try it again.

Also be sure to declare it scriptable='true' when deploying. Like this:

<applet 
    code="TestApplet" 
    name="AppTest"
    scriptable="true"
    height="350" 
    width="100">
</applet>

Most browsers will allow an applet to be called without it, but best to add it for the others.

answered Sep 17, 2013 at 16:38

Andrew Thompson

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1 Comment

adam5990 Over a year ago

This solution was correct, it just didn't work for me at first because of a server issue I had been unaware of. Thanks.

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