Java 8 – functional interfaces and abstract classes

See English answers > java 8: virtual extension methods vs Abstract Class5

According to my understanding, these interfaces can have some default implementation methods:

@FunctionalInterface
public interface ComplexFunctionalInterface extends SimpleFuncInterface 
{
    default public void doSomeWork()
    {
        System.out.println("Doing some work in interface impl...");
    }
    default public void doSomeOtherWork()
    {
        System.out.println("Doing some other work in interface impl...");
    }
}

But what I suspect is that this is the purpose of abstract classes

Why introduce functional interfaces

Solution

@H_ 301_ 15@

But my doubt is,this what abstract class is for.

Why introduce functional interfaces.

Number of classes that can be extended: 1

Number of realizable interfaces: more than 1