1 /* 2 * Copyright (c) 2003, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 */ 23 24 package pkg1; 25 26 /* 27 * Example from JSR 201, which borrowed it from "Effective Java". 28 */ 29 30 /** 31 * Arithmetic operations. 32 */ 33 public abstract enum Operation { 34 /** Addition */ 35 plus { 36 /** Add 'em up. */ 37 double eval(double x, double y) { return x + y; } 38 }, 39 minus { 40 double eval(double x, double y) { return x - y; } 41 }, 42 times { 43 double eval(double x, double y) { return x * y; } 44 }, 45 divided_by { 46 double eval(double x, double y) { return x / y; } 47 }; 48 49 /** 50 * Perform arithmetic operation represented by this constant. 51 */ 52 abstract double eval(double x, double y); 53 }