Java Rich Internet Applications Guide > Applet Developer's Guide > Applet Status and Event Handlers
Beginning in the Java SE 7 release, you can check the value of
the status variable of an applet while it is being
initialized. This check is non-blocking and immediately returns the
status of the applet. You can explicitly check the status of the
applet while it is loading and perform relevant actions or register
event handlers that will automatically be invoked during various
stages of applet initialization. The applet should be deployed with
the java_status_events parameter set to
true in order to use this functionality. See the
Handling Initialization Status With Event Handlers topic in the
Java Tutorials for step by step instructions and an example.
The following table displays the meaning of values returned by
the status method of the applet.
| Applet Status | Applet Status Variable Value | Meaning |
|---|---|---|
| LOADING | 1 | Applet is loading |
| READY | 2 | Applet has loaded completely and is ready to receive JavaScript calls |
| ERROR | 3 | Error while loading applet |
You can register event handlers for various events. The Java Plug-in software will invoke these event handlers at various stages of the applet loading process. The following table describes applet events for which event handlers can be registered.
| Applet Event | When Event Occurs |
|---|---|
| onLoad | Occurs when applet status is READY. Applet has finished loading and is ready to receive JavaScript calls |
| onStop | Occurs when applet has stopped |
| onError | Occurs when applet status is ERROR. An error has occurred while loading the applet |
You can register or determine an event handler in the JavaScript code of a web page as shown in the following code snippets.
// use an anonymous function
applet.onLoad(function() {
//event handler for ready state
}
// use a regular function
function onLoadHandler() {
// event handler for ready state
}
// Use method form
applet.onLoad(onLoadHandler);
// Use attribute form
applet.onLoad = onLoadHandler;
// get current event handler
var handler = applet.onLoad
