Implementing two interfaces with two default methods of the same signature in Java 8

Question

Suppose I have two interfaces:

public interface I1
{
    default String getGreeting() {
        return \"Good Morning!\";
    }
}

public interface I2
{
             


        

Answer 1

I believe the rule is that the class implementing the duplicate default methods 'must' override the implementation.. The following compiles and runs fine...

public class DupeDefaultInterfaceMethods {

interface FirstAbility {
    public default boolean doSomething() {
        return true;
    }
}

interface SecondAbility {
    public default boolean doSomething() {
        return true;
    }
}

class Dupe implements FirstAbility, SecondAbility {
    @Override
    public boolean doSomething() {
        return false;
    }
}

public static void main(String[] args) {
    DupeDefaultInterfaceMethods ddif = new DupeDefaultInterfaceMethods();
    Dupe dupe = ddif.new Dupe();
    System.out.println(dupe.doSomething());

    }
}

---

> false