Question

class Cat{
}

class Tiger extends Cat{
    public String getZooAddress(){
        return "cityZoo";
    };
}

Bean{
    public Cat getCat() {
        return new Tiger();
    }
}

I noticed that #{bean.cat.zooAddress} actually displays “cityZoo”. How does it work? I imagined that #{bean.cat} represents a Cat and trying to call getZooAddress() would result in an “property not found” error. Is the container automatically doing the downcasting from Cat to Tiger?

Answer 1

Expression Language utilizes Reflection to find the appropriate property accessor methods on the referenced object.

Here is more information on why Expression Language happens to work this way.

http://today.java.net/pub/a/today/2006/03/07/unified-jsp-jsf-expression-language.html#evaluation-of-el