Why do I get a Javascript error using a String returned from a Java Applet to index an array?

 You might get the error: IncompatibleClassChangeError java.lang.String:?

A Java String returned to JavaScript is wrapped by a JavaScript method object. When this object is used in an expression requiring a string, the wrapper's toString() method is called and a JavaScript String is returned. Since Array indexing is an implied polymorphic method (integer index or string property name), the toString() method is not called and the indexing method fails with this error. 4.0 handles this however. [4.0]

A simple workaround in 3.x is to force the conversion to a string.

For example:

var fred = myAppLet.spouse("wilma")
myDoc.myForm.elements[fred ].clicke// this yields the error
myDoc.myForm.elements[""+fred].clicke