Interface contains only abstact methods. In other words, interface provides only method signatures and actual implementation of the methods is left to subclasses.
Interface can not be instantiated. It can only be implemented by sub class.
What is difference between Abstract class and Interface?
Abstract class may contain one or more concrete class. Interface contain only abstract methods and does not provide default implementation.
Only one Abstract class can be extended by subclass as JVM does not allow multiple inheritance. However, a class can implement more than one interface and by that way class can achieve multiple interface inheritance.