java11-default-methods-conflicts

Overview of default methods conflicts.

project description

super class with interface conflict

base class

class CustomClass extends SuperClass implements Interface1 {}

super class

class SuperClass {
    public String get() {
        return "SuperClass";
    }
}

interface

interface Interface1 {
    default String get() {
        return "Interface1";
    }
}

then if you call method get() on an instance of CustomClass it will be called method from SuperClass:

assertThat(new CustomClass().get(), is("SuperClass"));

Note that If we narrow scope of get() method in superclass

class SuperClass {
    String get() {
        return "SuperClass";
    }
}

we obtain compile time error under

class CustomClass extends SuperClass implements Interface1 {}