Java Interfaces? [closed]

Solution 1:

What is an Interface? from Java's official tutorial

Edit: A second resource from the same tutorial, is the Interfaces and Inheritence section.

Solution 2:

In general:

You can see an interface as a contract or an agreement between two parties. So they can develop independently as long as the interface does not change.

The calling party, knows which behaviour is available and the implementing party knows what to implement.

There are a lot of advantages by using interfaces. One of them is that it is easy to switch between implementations. The other one is that classes can have different (inter)faces without using multiple inheritance.