SortItem.java

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 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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/*
 * This source code is provided to illustrate the usage of a given feature
 * or technique and has been deliberately simplified. Additional steps
 * required for a production-quality application, such as security checks,
 * input validation and proper error handling, might not be present in
 * this sample code.
 */
 
 
 
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
 
 
@SuppressWarnings("serial")
public class SortItem extends java.applet.Applet implements Runnable,
        MouseListener {
 
    private Thread kicker;
    int arr[];
    int h1 = -1;
    int h2 = -1;
    String algName;
    SortAlgorithm algorithm;
    Dimension initialSize = null;
 
    void scramble() {
        initialSize = getSize();
        int a[] = new int[initialSize.height / 2];
        double f = initialSize.width / (double) a.length;
 
        for (int i = a.length; --i >= 0;) {
            a[i] = (int) (i * f);
        }
        for (int i = a.length; --i >= 0;) {
            int j = (int) (i * Math.random());
            int t = a[i];
            a[i] = a[j];
            a[j] = t;
        }
        arr = a;
    }
 
    void pause() {
        pause(-1, -1);
    }
 
    void pause(int H1) {
        pause(H1, -1);
    }
 
    void pause(int H1, int H2) {
        h1 = H1;
        h2 = H2;
        if (kicker != null) {
            repaint();
        }
        try {
            Thread.sleep(20);
        } catch (InterruptedException e) {
        }
    }
 
    @Override
    public void init() {
        String at = getParameter("alg");
        if (at == null) {
            at = "BubbleSort";
        }
 
        algName = at + "Algorithm";
        scramble();
 
        resize(100, 100);
        addMouseListener(this);
    }
 
    @Override
    public void start() {
        h1 = h2 = -1;
        scramble();
        repaint();
        showStatus(getParameter("alg"));
    }
 
    @Override
    public void destroy() {
        removeMouseListener(this);
    }
 
    @Override
    public void paint(Graphics g) {
        int a[] = arr;
        int y = 0;
        int deltaY = 0, deltaX = 0, evenY = 0;
 
        Dimension currentSize = getSize();
        int currentHeight = currentSize.height;
        int currentWidth = currentSize.width;
 
        // Check to see if the applet has been resized since it
        // started running.  If so, need the deltas to make sure
        // the applet is centered in its containing panel.
        // The evenX and evenY are because the high and low
        // watermarks are calculated from the top, but the rest
        // of the lines are calculated from the bottom, which
        // can lead to a discrepancy if the window is not an
        // even size.
        if (!currentSize.equals(initialSize)) {
            evenY = (currentHeight - initialSize.height) % 2;
            deltaY = (currentHeight - initialSize.height) / 2;
            deltaX = (currentWidth - initialSize.width) / 2;
 
            if (deltaY < 0) {
                deltaY = 0;
                evenY = 0;
            }
            if (deltaX < 0) {
                deltaX = 0;
            }
        }
 
        // Erase old lines
        g.setColor(getBackground());
        y = currentHeight - deltaY - 1;
        for (int i = a.length; --i >= 0; y -= 2) {
            g.drawLine(deltaX + arr[i], y, currentWidth, y);
        }
 
        // Draw new lines
        g.setColor(Color.black);
        y = currentHeight - deltaY - 1;
        for (int i = a.length; --i >= 0; y -= 2) {
            g.drawLine(deltaX, y, deltaX + arr[i], y);
        }
 
        if (h1 >= 0) {
            g.setColor(Color.red);
            y = deltaY + evenY + h1 * 2 + 1;
            g.drawLine(deltaX, y, deltaX + initialSize.width, y);
        }
        if (h2 >= 0) {
            g.setColor(Color.blue);
            y = deltaY + evenY + h2 * 2 + 1;
            g.drawLine(deltaX, y, deltaX + initialSize.width, y);
        }
    }
 
    @Override
    public void update(Graphics g) {
        paint(g);
    }
 
    @Override
    public void run() {
        try {
            if (algorithm == null) {
                algorithm = (SortAlgorithm) Class.forName(algName).newInstance();
                algorithm.setParent(this);
            }
            algorithm.init();
            algorithm.sort(arr);
        } catch (Exception e) {
        }
    }
 
    @Override
    public synchronized void stop() {
        if (algorithm != null) {
            try {
                algorithm.stop();
            } catch (IllegalThreadStateException e) {
                // ignore this exception
            }
            kicker = null;
        }
    }
 
    private synchronized void startSort() {
        if (kicker == null || !kicker.isAlive()) {
            kicker = new Thread(this);
            kicker.start();
        }
    }
 
    @Override
    public void mouseClicked(MouseEvent e) {
        showStatus(getParameter("alg"));
    }
 
    @Override
    public void mousePressed(MouseEvent e) {
    }
 
    @Override
    public void mouseReleased(MouseEvent e) {
        startSort();
        e.consume();
    }
 
    @Override
    public void mouseEntered(MouseEvent e) {
    }
 
    @Override
    public void mouseExited(MouseEvent e) {
    }
 
    @Override
    public String getAppletInfo() {
        return "Title: SortDemo \nAuthor: James Gosling 1.17f, 10 Apr 1995 \nA simple applet class to demonstrate a sort algorithm.  \nYou can specify a sorting algorithm using the 'alg' attribute.  \nWhen you click on the applet, a thread is forked which animates \nthe sorting algorithm.";
    }
 
    @Override
    public String[][] getParameterInfo() {
        String[][] info = {
            { "alg", "string",
                "The name of the algorithm to run.  You can choose from the provided algorithms or suppply your own, as long as the classes are runnable as threads and their names end in 'Algorithm.'  BubbleSort is the default.  Example:  Use 'QSort' to run the QSortAlgorithm class." }
        };
        return info;
    }
}