This program animates a sort algorithm : Comparator « Collections Data Structure « Java





This program animates a sort algorithm

 
/*
   This program is a part of the companion code for Core Java 8th ed.
   (http://horstmann.com/corejava)

   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 3 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, see <http://www.gnu.org/licenses/>.
*/

import java.awt.BorderLayout;
import java.awt.EventQueue;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.geom.Rectangle2D;
import java.util.Arrays;
import java.util.Comparator;
import java.util.concurrent.Semaphore;

import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JPanel;

/**
 * This program animates a sort algorithm.
 * @version 1.01 2007-05-18
 * @author Cay Horstmann
 */
public class AlgorithmAnimation
{
   public static void main(String[] args)
   {
      EventQueue.invokeLater(new Runnable()
         {
            public void run()
            {
               JFrame frame = new AnimationFrame();
               frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
               frame.setVisible(true);
            }
         });
   }
}

/**
 * This frame shows the array as it is sorted, together with buttons to single-step the animation or
 * to run it without interruption.
 */
class AnimationFrame extends JFrame
{
   public AnimationFrame()
   {
      ArrayComponent comp = new ArrayComponent();
      add(comp, BorderLayout.CENTER);

      final Sorter sorter = new Sorter(comp);

      JButton runButton = new JButton("Run");
      runButton.addActionListener(new ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               sorter.setRun();
            }
         });

      JButton stepButton = new JButton("Step");
      stepButton.addActionListener(new ActionListener()
         {
            public void actionPerformed(ActionEvent event)
            {
               sorter.setStep();
            }
         });

      JPanel buttons = new JPanel();
      buttons.add(runButton);
      buttons.add(stepButton);
      add(buttons, BorderLayout.NORTH);
      setSize(DEFAULT_WIDTH, DEFAULT_HEIGHT);

      Thread t = new Thread(sorter);
      t.start();
   }

   private static final int DEFAULT_WIDTH = 300;
   private static final int DEFAULT_HEIGHT = 300;
}

/**
 * This runnable executes a sort algorithm. When two elements are compared, the algorithm pauses and
 * updates a component.
 */
class Sorter implements Runnable
{
   /**
    * Constructs a Sorter.
    * @param values the array to be sorted
    * @param comp the component on which to display the sorting progress
    */
   public Sorter(ArrayComponent comp)
   {
      values = new Double[VALUES_LENGTH];
      for (int i = 0; i < values.length; i++)
         values[i] = new Double(Math.random());
      this.component = comp;
      this.gate = new Semaphore(1);
      this.run = false;
   }

   /**
    * Sets the sorter to "run" mode. Called on the event dispatch thread.
    */
   public void setRun()
   {
      run = true;
      gate.release();
   }

   /**
    * Sets the sorter to "step" mode. Called on the event dispatch thread.
    */
   public void setStep()
   {
      run = false;
      gate.release();
   }

   public void run()
   {
      Comparator<Double> comp = new Comparator<Double>()
         {
            public int compare(Double i1, Double i2)
            {
               component.setValues(values, i1, i2);
               try
               {
                  if (run) Thread.sleep(DELAY);
                  else gate.acquire();
               }
               catch (InterruptedException exception)
               {
                  Thread.currentThread().interrupt();
               }
               return i1.compareTo(i2);
            }
         };
      Arrays.sort(values, comp);
      component.setValues(values, null, null);
   }

   private Double[] values;
   private ArrayComponent component;
   private Semaphore gate;
   private static final int DELAY = 100;
   private volatile boolean run;
   private static final int VALUES_LENGTH = 30;
}

/**
 * This component draws an array and marks two elements in the array.
 */
class ArrayComponent extends JComponent
{
   /**
    * Sets the values to be painted. Called on the sorter thread.
    * @param values the array of values to display
    * @param marked1 the first marked element
    * @param marked2 the second marked element
    */
   public synchronized void setValues(Double[] values, Double marked1, Double marked2)
   {
      this.values = values.clone();
      this.marked1 = marked1;
      this.marked2 = marked2;
      repaint();
   }

   public synchronized void paintComponent(Graphics g) // Called on the event dispatch thread
   {
      if (values == null) return;
      Graphics2D g2 = (Graphics2D) g;
      int width = getWidth() / values.length;
      for (int i = 0; i < values.length; i++)
      {
         double height = values[i] * getHeight();
         Rectangle2D bar = new Rectangle2D.Double(width * i, 0, width, height);
         if (values[i] == marked1 || values[i] == marked2) g2.fill(bar);
         else g2.draw(bar);
      }
   }

   private Double marked1;
   private Double marked2;
   private Double[] values;
}

   
  










Related examples in the same category

1.Creating a Comparable objectCreating a Comparable object
2. Writing Your own Comparator Writing Your own Comparator
3.A Class Implementing Comparable
4.Comparator for comparing strings ignoring first character
5.List and Comparators
6.Sort backwards
7.Company and Employee
8.Search with a Comparator
9.Keep upper and lowercase letters togetherKeep upper and lowercase letters together
10.Uses anonymous inner classesUses anonymous inner classes
11.Building the anonymous inner class in-placeBuilding the anonymous inner class in-place
12.Sort an array of strings in reverse order.
13.Sort an array of strings, ignore case difference.
14.Comparator uses a Collator to determine the proper, case-insensitive lexicographical ordering of two strings.
15.Using the Comparable interface to compare and sort objects
16.Sort on many(more than one) fields
17.File Name Comparator
18.Comparator similar to String.CASE_INSENSITIVE_ORDER, but handles only ASCII characters
19.Natural Order Comparator
20.Reverse Order Comparator
21.A Comparator for Boolean objects that can sort either true or false first
22.Invertible Comparator