Comments on: JSTL, instanceof, and hasProperty

By: sbk

sbk — Thu, 10 May 2012 09:19:51 +0000

Thanks for this post which was most useful for me today. FYI org.apache.commons.beanutils.PropertyUtils could futher simplify your code (if you are happy with the dependency of course):

public static boolean hasProperty(Object o, String propertyName) {
if (o == null || propertyName == null) {
return false;
}
try
{
return PropertyUtils.getPropertyDescriptor(o, propertyName) != null;
}
catch (Exception e)
{
return false;
}
}

By: vivin

vivin — Thu, 11 Aug 2011 21:41:42 +0000

Thanks for the improvements! I’m adding them to the original post.

By: thetoolman

thetoolman — Thu, 11 Aug 2011 21:35:28 +0000

insanceOf now uses the callers classloader, and hasProperty now uses BeanInfo for inspection instead of doing it by hand

By: thetoolman

thetoolman — Thu, 11 Aug 2011 21:32:47 +0000

Thanks for posting; here is some improvements for your code:

public static boolean instanceOf(Object o, String className) {
if (o == null || className == null) {
return false;
}
try {
return Class.forName(className, false, Thread.currentThread().getContextClassLoader()).isInstance(o);
} catch (ClassNotFoundException e) {
return false;
}
}

public static boolean hasProperty(Object o, String propertyName) {
if (o == null || propertyName == null) {
return false;
}
BeanInfo beanInfo;
try {
beanInfo = java.beans.Introspector.getBeanInfo(o.getClass());

} catch (IntrospectionException e) {
return false;
}

for (final PropertyDescriptor pd : beanInfo.getPropertyDescriptors()) {
if (propertyName.equals(pd.getName())) {
return true;
}
}

return false;
}

By: vivin

vivin — Thu, 17 Dec 2009 02:23:03 +0000

No problem! Glad you found it useful.

By: Kalyan

Kalyan — Tue, 15 Dec 2009 17:33:11 +0000

Thanks for posting this example Vivin.