Inheritance.java

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public class Inheritance {
 
    public interface Swimable {
 
        default String swim() {
            return "I can swim.";
        }
    }
 
    public abstract static class Fish implements Swimable {
 
        @Override
        public String swim() {
            return this.getClass().getSimpleName() + " swims under water";
        }
    }
 
    public static class Tuna extends Fish implements Swimable {
    }
 
    public interface Diveable extends Swimable {
 
        @Override
        default String swim() {
            return "I can swim on the surface of the water.";
        }
 
        default String dive() {
            return "I can dive.";
        }
    }
 
    public static class Duck implements Swimable, Diveable {
    }
 
    public static void main(final String[] args) {
        // Illustrates rule 1. The Fish.swim() implementation wins
        //"Tuna swims under water" is output
        System.out.println(new Tuna().swim());
 
        // Illustrates rule 2. The Diveable.swim() implementation wins
        //"I can swim on the surface of the water." is output
        System.out.println(new Duck().swim());
    }
}