abstract class vs interface

Anyone who have idea when we should use abstract class and when interface.

The Java Tutorial mentions both. It should be easy to figure out the appropriate use of each.

See this thread for a "world of nature" example of interface vs. abstract class.

Here are two general guidelines that might help:
First: An interface cannot contain any implementation whatsoever. (Thus, all methods are abstract.) An abstract class can contain as much implementation as you desire. (For example, an asbstract class can contain one or more fully implemented methods.) Therefore, if you want to supply a partial implementation, use an abstract class. Otherwise, use an interface.
Second: A class can implement multiple interfaces. It can only inherit one abstract class. Thus, if you want a class to be able to implement two or more "interfaces", they must be interfaces, not abstract classes.

Correct me if I'm wrong. To me, interface in java is about as close as java gets with multiple inheritance, remember, java doesn't allow multiple inheritance. However, interface allows you to do that in a sense.