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JavaScript: The Definitive Guide

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JavaScript Reference

getClass() Function


getClass() Function---return the JavaClass of a JavaObject


Navigator 3.0





A JavaObject object.


The JavaClass object of javaobj.


getClass() is a function that takes a JavaObject object (javaobj) as an argument. It returns the JavaClass object that JavaObject. That is, it returns the JavaClass object that represents the Java class of the Java object represented by the specified JavaObject.


Don't confuse the JavaScript getClass() function with the getClass method of all Java objects. Similarly, don't confuse the JavaScript JavaClass object with the Java java.lang.Class class.

Consider the Java rectangle object created with the following line:

var r = new java.awt.Rectangle();

r is a JavaScript variable that holds a JavaObject object. Calling the JavaScript function getClass() returns a JavaClass object that represents the java.awt.Rectangle class:

var c = getClass(r);

You can see that this is so by comparing this JavaClass object to java.awt.Rectangle:

if (c == java.awt.Rectangle) ...

The Java getClass() method is invoked differently and performs an entirely different function:

c = r.getClass();

After executing the above line of code, c is a JavaObject that represents a java.lang.Class object. This java.lang.Class object is a Java object that is a Java representation of the java.awt.Rectangle class. See your Java documentation for details on what you can do with the java.lang.Class class.

To summarize, you can see that the following expression will always evaluate to true, for any JavaObject o:

(getClass(o.getClass()) == java.lang.Class)

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