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/*
* Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* - Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* - Neither the name of Oracle nor the names of its
* contributors may be used to endorse or promote products derived
* from this software without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
* IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
* THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
/**
* The sample illustrates rules to resolve conflicts between inheritance
* candidates with <b>default methods</b>. There are two simple rules:
* <ul>
* <li>Class wins. If the superclass has a concrete or abstract declaration of
* this method, then it is preferred over all defaults.</li>
* <li>Subtype wins. If an interface extends another interface, and both provide
* a default, then the more specific interface wins. </li>
* </ul>
*/
public class Inheritance {
/**
* The behavior of an creature that can swim
*/
public interface Swimable {
/**
* Return string representation of the swim action for a creature that
* can swim
*
* @return string representation of the swim action for a creature
* that can swim
*/
default String swim() {
return "I can swim.";
}
}
/**
* The abstract class that overrides {@link #swim} method
*/
public abstract static class Fish implements Swimable {
/**
* Return string representation of the swim action for a fish
*
* @return string representation of the swim action for a fish
*/
@Override
public String swim() {
return this.getClass().getSimpleName() + " swims under water";
}
}
/**
* This class is used for the illustration rule of 1. See the source code
* of the {@link #main} method.
* <pre>
* System.out.println(new Tuna().swim()); //"Tuna swims under water" output is suspected here
* </pre>
*/
public static class Tuna extends Fish implements Swimable {
}
/**
* The behavior of an creature that can dive: the interface that overrides
* {@link #swim} method (subtype of {@link Swimable})
*/
public interface Diveable extends Swimable {
/**
* Return string representation of the swim action for a creature that
* can dive
*
* @return string representation of the swim action for a creature
* that can dive
*/
@Override
default String swim() {
return "I can swim on the surface of the water.";
}
/**
* Return string representation of the dive action for a creature that
* can dive
*
* @return string representation of the dive action for a creature
* that can dive
*/
default String dive() {
return "I can dive.";
}
}
/**
* This class is used for the illustration of rule 2. See the source code
* of the {@link #main} method
* <pre>
* //"I can swim on the surface of the water." output is suspected here
* System.out.println(new Duck().swim());
* </pre>
*/
public static class Duck implements Swimable, Diveable {
}
/**
* Illustrate behavior of the classes: {@link Tuna} and {@link Duck}
*
* @param args command line arguments
*/
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());
}
}
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