Passing JS function to applet for as event listener

Question

Is it possible to pass a function/callback from javascript to a java applet?

For example i have an applet with a button that when pressed it will call the passed js callback

function onCommand() {alert('Button pressed from applet');}
applet.onCommand(onCommand);

Answer 1

You can use JSObject to call back into javascript from Java.

From that page:

import netscape.javascript.*;
import java.applet.*;
import java.awt.*;
class MyApplet extends Applet {
     public void init() {
         JSObject win = JSObject.getWindow(this);
         JSObject doc = (JSObject) win.getMember("document");
         JSObject loc = (JSObject) doc.getMember("location");

         String s = (String) loc.getMember("href");  // document.location.href
         win.call("f", null);                      // Call f() in HTML page
     }
}

Answer 2

I tend to use something I derived from the reflection example at the bottom of this page, as then you don't need to meddle with your classpath to get it to compile

Then I just pass JSON strings around between the applet and javascript

Answer 3

ps. to use JSObject you may need to include "MAYSCRIPT" tag to applet html tag.