1 /*
   2  * Copyright (c) 2019, 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 examples;
  25 
  26 /**
  27  * Two-dimensional coordinates that can be represented
  28  * in either Cartesian or polar form.
  29  */
  30 public interface Coords {
  31 
  32     /**
  33      * Returns the Cartesian x-coordinate.
  34      *
  35      * @return the Cartesian x-coordinate
  36      */
  37     public double x();
  38 
  39     /**
  40      * Returns the Cartesian y-coordinate.
  41      *
  42      * @return the Cartesian y-coordinate
  43      */
  44     public double y();
  45 
  46     /**
  47      * Returns the polar r-coordinate, or radius.
  48      *
  49      * @return the polar r-coordinate
  50      */
  51     public double r();
  52 
  53     /**
  54      * Returns the polar theta-coordinate, or angle.
  55      *
  56      * @return the polar theta-coordinate
  57      */
  58     public double theta();
  59 
  60     /**
  61       * Cartesian coordinates.
  62       *
  63       * @param x the x-coordinate
  64       * @param y the y-coordinate
  65       */
  66     public record Cartesian(double x, double y) implements Coords {
  67         @Override
  68         public double r() {
  69             return Math.sqrt(x * x + y * y);
  70         }
  71 
  72         @Override
  73         public double theta() {
  74             return (x == 0) ? Math.PI / 2.d : Math.atan(y / x);
  75         }
  76     }
  77 
  78     /**
  79       * Polar coordinates.
  80       *
  81       * @param r     the radius
  82       * @param theta the angle
  83       */
  84     public record Polar(double r, double theta) implements Coords {
  85         @Override
  86         public double x() {
  87           return r * Math.cos(theta);
  88         }
  89 
  90         @Override
  91         public double y() {
  92           return r * Math.sin(theta);
  93         }
  94     }
  95 }