Java Tutorial/2D Graphics/Polygon

Draw Polygon

   <source lang="java">

import java.awt.Graphics; import javax.swing.JComponent; import javax.swing.JFrame; class MyCanvas extends JComponent {

 public void paint(Graphics g) {
   int[] x = new int[]{100,200,300,400};
   int[] y = new int[]{400,300,300,100};
   g.drawPolygon (x, y, x.length);    
 }

} public class DrawPolygon {

 public static void main(String[] a) {
   JFrame window = new JFrame();
   window.setBounds(30, 30, 300, 300);
   window.getContentPane().add(new MyCanvas());
   window.setVisible(true);
 }

}</source>

Tests two polygons for equality. If both are null this method returns true.

   <source lang="java">

/*

* JCommon : a free general purpose class library for the Java(tm) platform
* 
*
* (C) Copyright 2000-2008, by Object Refinery Limited and Contributors.
*
* Project Info:  http://www.jfree.org/jcommon/index.html
*
* This library is free software; you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by
* the Free Software Foundation; either version 2.1 of the License, or
* (at your option) any later version.
*
* This library 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 Lesser General Public
* License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301,
* USA.
*
* [Java is a trademark or registered trademark of Sun Microsystems, Inc.
* in the United States and other countries.]
*
* -------------------
* ShapeUtilities.java
* -------------------
* (C)opyright 2003-2008, by Object Refinery Limited and Contributors.
*
* Original Author:  David Gilbert (for Object Refinery Limited);
* Contributor(s):   -;
*
* $Id: ShapeUtilities.java,v 1.18 2008/06/02 06:58:28 mungady Exp $
*
* Changes
* -------
* 13-Aug-2003 : Version 1 (DG);
* 16-Mar-2004 : Moved rotateShape() from RefineryUtilities.java to here (DG);
* 13-May-2004 : Added new shape creation methods (DG);
* 30-Sep-2004 : Added createLineRegion() method (DG);
*               Moved drawRotatedShape() method from RefineryUtilities class
*               to this class (DG);
* 04-Oct-2004 : Renamed ShapeUtils --> ShapeUtilities (DG);
* 26-Oct-2004 : Added a method to test the equality of two Line2D
*               instances (DG);
* 10-Nov-2004 : Added new translateShape() and equal(Ellipse2D, Ellipse2D)
*               methods (DG);
* 11-Nov-2004 : Renamed translateShape() --> createTranslatedShape() (DG);
* 07-Jan-2005 : Minor Javadoc fix (DG);
* 11-Jan-2005 : Removed deprecated code in preparation for 1.0.0 release (DG);
* 21-Jan-2005 : Modified return type of RectangleAnchor.coordinates()
*               method (DG);
* 22-Feb-2005 : Added equality tests for Arc2D and GeneralPath (DG);
* 16-Mar-2005 : Fixed bug where equal(Shape, Shape) fails for two Polygon
*               instances (DG);
* 01-Jun-2008 : Fixed bug in equal(GeneralPath, GeneralPath) method (DG);
*
*/

import java.awt.Shape; import java.awt.geom.GeneralPath; import java.awt.geom.PathIterator; import java.util.Arrays; /**

* Utility methods for {@link Shape} objects.
*
* @author David Gilbert
*/

public class Main {

 /**
  * Tests two polygons for equality.  If both are null this
  * method returns true.
  *
  * @param p1  path 1 (null permitted).
  * @param p2  path 2 (null permitted).
  *
  * @return A boolean.
  */
 public static boolean equal(final GeneralPath p1, final GeneralPath p2) {
     if (p1 == null) {
         return (p2 == null);
     }
     if (p2 == null) {
         return false;
     }
     if (p1.getWindingRule() != p2.getWindingRule()) {
         return false;
     }
     PathIterator iterator1 = p1.getPathIterator(null);
     PathIterator iterator2 = p2.getPathIterator(null);
     double[] d1 = new double[6];
     double[] d2 = new double[6];
     boolean done = iterator1.isDone() && iterator2.isDone();
     while (!done) {
         if (iterator1.isDone() != iterator2.isDone()) {
             return false;
         }
         int seg1 = iterator1.currentSegment(d1);
         int seg2 = iterator2.currentSegment(d2);
         if (seg1 != seg2) {
             return false;
         }
         if (!Arrays.equals(d1, d2)) {
             return false;
         }
         iterator1.next();
         iterator2.next();
         done = iterator1.isDone() && iterator2.isDone();
     }
     return true;
 }

}</source>