1 /* 2 * Copyright (c) 2014, Oracle and/or its affiliates. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * - Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 11 * - Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * - Neither the name of Oracle nor the names of its 16 * contributors may be used to endorse or promote products derived 17 * from this software without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS 20 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, 21 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR 23 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 24 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 25 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR 26 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF 27 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING 28 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS 29 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 30 */ 31 32 /** 33 * This sample diamond interface inheritance with <b>default methods</b>. 34 * If there's not already a unique method implementation to inherit, 35 * you must provide it. The inheritance diagram is similar to the following: 36 * <pre> 37 * Animal 38 * / \ 39 * Horse Bird 40 * \ / 41 * Pegasus 42 * </pre> 43 * 44 * Both {@link Horse} and {@link Bird} interfaces implements the <code>go</code> 45 * method. The {@link Pegasus} class have to overrides the 46 * <code>go</code> method. 47 * 48 * The new syntax of super-call is used here: 49 * <pre> 50 * <interface_name>.super.<method>(...); 51 * For example: Horse.super.go(); 52 * </pre> So, Pegasus moves like a horse. 53 */ 54 public class DiamondInheritance { 55 56 /** 57 * Base interface to illustrate the diamond inheritance. 58 * 59 * @see DiamondInheritance 60 */ 61 public interface Animal { 62 63 /** 64 * Return string representation of the "go" action for concrete animal 65 * 66 * @return string representation of the "go" action for concrete animal 67 */ 68 String go(); 69 } 70 71 /** 72 * Interface to illustrate the diamond inheritance. 73 * 74 * @see DiamondInheritance 75 */ 76 public interface Horse extends Animal { 77 78 /** 79 * Return string representation of the "go" action for horse 80 * 81 * @return string representation of the "go" action for horse 82 */ 83 @Override 84 default String go() { 85 return this.getClass().getSimpleName() + " walks on four legs"; 86 } 87 } 88 89 /** 90 * Interface to illustrate the diamond inheritance. 91 * 92 * @see DiamondInheritance 93 */ 94 public interface Bird extends Animal { 95 96 /** 97 * Return string representation of the "go" action for bird 98 * 99 * @return string representation of the "go" action for bird 100 */ 101 @Override 102 default String go() { 103 return this.getClass().getSimpleName() + " walks on two legs"; 104 } 105 106 /** 107 * Return string representation of the "fly" action for bird 108 * 109 * @return string representation of the "fly" action for bird 110 */ 111 default String fly() { 112 return "I can fly"; 113 } 114 } 115 116 /** 117 * Class to illustrate the diamond inheritance. Pegasus must mix horse and 118 * bird behavior. 119 * 120 * @see DiamondInheritance 121 */ 122 public static class Pegasus implements Horse, Bird { 123 124 /** 125 * Return string representation of the "go" action for the fictitious 126 * creature Pegasus 127 * 128 * @return string representation of the "go" action for the fictitious 129 * creature Pegasus 130 */ 131 @Override 132 public String go() { 133 return Horse.super.go(); 134 } 135 } 136 137 /** 138 * Illustrate the behavior of the {@link Pegasus} class 139 * 140 * @param args command line arguments 141 */ 142 public static void main(final String[] args) { 143 System.out.println(new Pegasus().go()); 144 } 145 } 146
