CareerCup

Let’s take up this question in design point of view. Usually go for an abstract class when you have a set of classes having a common behavior. That abstract class can contain methods which are common for all the concrete classes which extend from it and have other methods implemented in their own way. For example, consider an abstract class Person; this class can be inherited by Jerry, Thompson and Verica. Because all three are human beings, they have certain features common to all human beings like hands, legs, head, neck etc, and they also differentiate themselves from others in terms of their own behavior (character). Go for interfaces when you want role specific behavior. In the above example, a person may perform multiple roles. For instance, Jerry may have roles such as Doctor (by profession), Father (to his children), Husband (to his wife) etc. Now we can have Doctor, Father and Husband as interfaces implemented by Jerry.
Code to an interface than an implementation
You would have come across the above quote many times. Here the word interface doesn't actually mean the interface in java. It just means coding to a super type than to the concrete sub type. It may be implemented either using interface or abstract class based on requirement.
To conclude, use abstract class and interface based on requirement (or design) and not for sake. Always think in terms of design than implementation. When they are used effectively, it improves code maintenance and re usability.

While the purpose of Interface and Abstract Class are same, Abstract Class can have implementation of the method and also fields. An Interface cannot have implementations of the method or any fields. And a class can extend only one Abstract Class, but can implement multiple interfaces.

Both interfaces and abstract class are used to establish contract with client code.
Use abstract classes when you have some code which can be reused by subclasses. So its like a template.When there is nothing reusable use interfaces.

interface allows multiple inheritance but Abstract Class does not

a 100% abstract class is a interface. :)