code: ///////////////////////////////////////////////////////////////////////////////
  // For information as to what this class does, see the Javadoc, below.       //
  // Copyright (C) 1998, 1999, 2000, 2001, 2002, 2003, 2004, 2005, 2006,       //
  // 2007, 2008, 2009, 2010, 2014, 2015 by Peter Spirtes, Richard Scheines, Joseph   //
  // Ramsey, and Clark Glymour.                                                //
  //                                                                           //
  // This program is free software; you can redistribute it and/or modify      //
  // it under the terms of the GNU General Public License as published by      //
  // the Free Software Foundation; either version 2 of the License, or         //
  // (at your option) any later version.                                       //
  //                                                                           //
  // This program is distributed in the hope that it will be useful,           //
  // but WITHOUT ANY WARRANTY; without even the implied warranty of            //
  // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the             //
  // GNU General Public License for more details.                              //
  //                                                                           //
  // You should have received a copy of the GNU General Public License         //
  // along with this program; if not, write to the Free Software               //
  // Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA //
  ///////////////////////////////////////////////////////////////////////////////
  
  package edu.cmu.tetrad.util;
  
  
  /**
   * Stores a (x, y) point without having to use awt classes. Immutable.
   *
   * @author Joseph Ramsey
   */
  public class PointXy implements TetradSerializable {
      static final long serialVersionUID = 23L;
  
      /**
       * The x coordinate.
       *
       * @serial
       */
      private final int x;
  
      /**
       * The y coordinate.
       *
       * @serial
       */
      private final int y;
  
      //=============================CONSTRUCTORS=======================//
  
      /**
       * Constructs a new point with the given coordinates.
       *
       * @param x The x coordinate for the point.
       * @param y The y coordinate for the point.
       */
      public PointXy(int x, int y) {
          this.x = x;
          this.y = y;
      }
  
      /**
       * Copy constructor.
       *
       * @param point The point to be copied.
       */
      public PointXy(PointXy point) {
          this.x = point.x;
          this.y = point.y;
      }
  
      /**
       * Generates a simple exemplar of this class to test serialization.
       *
       * @return the examplar.
       */
      @SuppressWarnings({"UnusedDeclaration"})
      public static PointXy serializableInstance() {
          return new PointXy(1, 2);
      }
  
      //=============================PUBLIC METHODS====================//
  
      /**
       * @return Ibid.
       */
      public int getX() {
          return x;
      }
  
      /**
       * @return Ibid.
       */
      public int getY() {
          return y;
      }
  
      /**
       * @return true just in case o is a Point with the same x and y
       * coordinates.
       */
      public boolean equals(Object o) {
          if (!(o instanceof PointXy)) {
              throw new IllegalArgumentException("Not a Point object.");
          }
  
          if (o == this) {
              return true;
          }
  
          PointXy c = (PointXy) o;
          return c.x == this.x && c.y == this.y;
      }
  
      /**
       * @return a string representation of a point.
       */
      public String toString() {
          return "Point<" + x + "," + y + ">";
      }
  }
  
  
  
  
  
  