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 }