RSS Feed
Download our iPhone app
Browse DevX
Sign up for e-mail newsletters from DevX


Tip: Testing if an Object can be Cast Using Instanceof

Learn how to test if an object is of a certain type, or a subclass of that type.


Java provides the instanceof operator to test if an object is of a certain type, or a subclass of that type. The program can then choose to cast or not cast that object accordingly.

Object obj = Calendar.getInstance(); 
long time = 0; 
if(obj instanceof Calendar) { 
time = ((Calendar)obj).getTime();
if(obj instanceof Date) { 
time = ((Date)obj).getTime(); // This line will never be reached, obj is not a Date type. 


Visit the DevX Tip Bank


Octavia Andreea Anghel is a senior PHP developer currently working as a primary trainer for programming teams that participate at national and international software-development contests. She consults on developing educational projects at a national level. She is a coauthor of the book "XML Technologies--XML in Java" (Albastra, ISBN 978-973-650-210-1), for which she wrote the XML portions. In addition to PHP and XML, she's interested in software architecture, web services, UML, and high-performance unit tests.
Email AuthorEmail Author
Close Icon
Thanks for your registration, follow us on our social networks to keep up-to-date