Starting from Java 8, a method which is defined in an interface can have a default implementation:
For example:
interface Descriptive {
    default String desc() {
        return "fantastic";
    }
}
class Item implements Descriptive {
    // the method "desc" is not implemented here
}
Item item = new Item();
item.desc(); // "fantastic"
class Book implements Descriptive {
    @Override
    public String desc() {
        return "Cool book!";
    }
}
Book book = new Book();
book.desc(); // "Cool book!"