Overriding the default interface method with an abstract method

Question

It seems to me that this is strange, and I was wondering if this is what is regularly used. When can this be helpful?

public interface InterA { Object getInfo() throws Exception1; } public interface InterB { public default Integer getInfo(Object s) {return 67;} } public interface InterC extends InterA, InterB { @Override public abstract Integer getInfo(Object s); } 

Answer 1

Of course, you are allowed to do this. The name itself says that it is abstract . You are allowed to do this when the implemented class of this abstract class must override this method.

When you decide to be abstract, you do not need to implement.

Answer 2

This exists before the default interface methods. For example, an abstract class can do

  @Override abstract public int hashCode(); 

forced subclasses provide implementations for hashCode , possibly due to additional requirements imposed by the abstract class.