/* * 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. */ /** * This sample diamond interface inheritance with <b>default methods</b>. * If there's not already a unique method implementation to inherit, * you must provide it. The inheritance diagram is similar to the following: * <pre> * Animal * / \ * Horse Bird * \ / * Pegasus * </pre> * * Both {@link Horse} and {@link Bird} interfaces implements the <code>go</code> * method. The {@link Pegasus} class have to overrides the * <code>go</code> method. * * The new syntax of super-call is used here: * <pre> * <interface_name>.super.<method>(...); * For example: Horse.super.go(); * </pre> So, Pegasus moves like a horse. */ public class DiamondInheritance { /** * Base interface to illustrate the diamond inheritance. * * @see DiamondInheritance */ public interface Animal { /** * Return string representation of the "go" action for concrete animal * * @return string representation of the "go" action for concrete animal */ String go(); } /** * Interface to illustrate the diamond inheritance. * * @see DiamondInheritance */ public interface Horse extends Animal { /** * Return string representation of the "go" action for horse * * @return string representation of the "go" action for horse */ @Override default String go() { return this.getClass().getSimpleName() + " walks on four legs"; } } /** * Interface to illustrate the diamond inheritance. * * @see DiamondInheritance */ public interface Bird extends Animal { /** * Return string representation of the "go" action for bird * * @return string representation of the "go" action for bird */ @Override default String go() { return this.getClass().getSimpleName() + " walks on two legs"; } /** * Return string representation of the "fly" action for bird * * @return string representation of the "fly" action for bird */ default String fly() { return "I can fly"; } } /** * Class to illustrate the diamond inheritance. Pegasus must mix horse and * bird behavior. * * @see DiamondInheritance */ public static class Pegasus implements Horse, Bird { /** * Return string representation of the "go" action for the fictitious * creature Pegasus * * @return string representation of the "go" action for the fictitious * creature Pegasus */ @Override public String go() { return Horse.super.go(); } } /** * Illustrate the behavior of the {@link Pegasus} class * * @param args command line arguments */ public static void main(final String[] args) { System.out.println(new Pegasus().go()); } }