import java.awt.*;import java.awt.event.MouseAdapter;import java.awt.event.MouseEvent;import java.io.InputStream;import java.util.Hashtable;import java.net.*;/** * A simple applet class to demonstrate a sort algorithm.該小應(yīng)用程序揭示一種排序算法 * You can specify a sorting algorithm using the "alg"讀者可以使用參數(shù)來(lái)確定使用的算法 * attribyte. When you click on the applet, a thread is當(dāng)用鼠標(biāo)單擊該小應(yīng)用程序時(shí)，屏幕上將使用動(dòng)畫來(lái)顯示算法的執(zhí)行過(guò)程 * forked which animates the sorting algorithm. */public class SortItem extends java.applet.Applet implements Runnable {    /**     * The thread that is sorting (or null).排序線程     */    private Thread kicker;    /**     * The array that is being sorted.被排序的數(shù)組     */    int arr[];    /**     * The high water mark.高水位標(biāo)記     */    int h1 = -1;    /**     * The low water mark.低水位標(biāo)記     */    int h2 = -1;    /**     * The name of the algorithm.排序算法的名稱     */    String algName;    /**     * The sorting algorithm (or null).排序算法     */    SortAlgorithm algorithm;    /**     * Fill the array with random numbers from 0...使用從0到n-1的隨機(jī)數(shù)填滿數(shù)組     */    void scramble() {	int a[] = new int[getSize().height / 2];	double f = getSize().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;    }    /**     * Pause a while.暫停，見(jiàn)SortAlgorithm程序      */    void pause() {	pause(-1, -1);    }    /**     * Pause a while, and draw the high water mark.暫停，并且標(biāo)出高水位     * 見(jiàn)SortAlgorithm程序     */    void pause(int H1) {	pause(H1, -1);    }    /**     * Pause a while, and draw the low&high water marks.暫停，并且標(biāo)出高水位&低水位     * @see 見(jiàn)SortAlgorithm程序     */    void pause(int H1, int H2) {	h1 = H1;	h2 = H2;	if (kicker != null) {	    repaint();	}	try {Thread.sleep(20);} catch (InterruptedException e){}    }    /**     * Initialize the applet.初始化小應(yīng)用程序     */    public void init() {	String at = getParameter("alg");	if (at == null) {	    at = "BubbleSort";	}	algName = at + "Algorithm";	scramble();	addMouseListener(new ClockStarter());	resize(100, 100);    }    /**     * Paint the array of numbers as a list將數(shù)組中的不同數(shù)字用長(zhǎng)度不同的水平線段來(lái)表示出來(lái)     * of horizontal lines of varying lenghts.     */    public void paint(Graphics g) {	int a[] = arr;	int y = getSize().height - 1;	// Erase old lines 消除舊的線段	g.setColor(getBackground());	for (int i = a.length; --i >= 0; y -= 2) {	    g.drawLine(arr[i], y, getSize().width, y);	}	// Draw new lines畫新線段	g.setColor(Color.black);	y = getSize().height - 1;	for (int i = a.length; --i >= 0; y -= 2) {	    g.drawLine(0, y, arr[i], y);	}	if (h1 >= 0) {	    g.setColor(Color.red);	    y = h1 * 2 + 1;	    g.drawLine(0, y, getSize().width, y);	}	if (h2 >= 0) {	    g.setColor(Color.blue);	    y = h2 * 2 + 1;	    g.drawLine(0, y, getSize().width, y);	}    }    /**     * Update without erasing the background.采用不消除背景的技術(shù)進(jìn)行更新     */    public void update(Graphics g) {	paint(g);    }    /**     * Run the sorting algorithm. This method is     * called by class Thread once the sorting algorithm     * is started.執(zhí)行排序算法，排序算法一旦開(kāi)始就啟動(dòng)該方法     * @see java.lang.Thread#run     * @see SortItem#mouseUp     */    public void run() {	try {	    if (algorithm == null) {		algorithm = (SortAlgorithm)Class.forName(algName).newInstance();		algorithm.setParent(this);	    }	    algorithm.init();	    algorithm.sort(arr);	} catch(Exception e) {	}    }    /**     * Stop the applet. Kill any sorting algorithm that     * is still sorting.停止小應(yīng)用程序，殺死一切正在進(jìn)行的排序算法     */    public synchronized void stop() {	if (kicker != null) {            try {		kicker.stop();            } catch (IllegalThreadStateException e) {                // ignore this exception忽略這個(gè)異常            }	    kicker = null;	}	if (algorithm != null){            try {		algorithm.stop();            } catch (IllegalThreadStateException e) {                // ignore this exception忽略這個(gè)異常            }	}    }    /**     * For a Thread to actually do the sorting. This routine makes為了使一個(gè)線程真正實(shí)現(xiàn)排序，確認(rèn)當(dāng)用戶重復(fù)的在小應(yīng)用程序上單擊鼠標(biāo)時(shí)，不同時(shí)啟動(dòng)多個(gè)線程     * sure we do not simultaneously start several sorts if the user     * repeatedly clicks on the sort item.  It needs to be它需要與方法同步     * synchronoized with the stop() method because they both     * manipulate the common kicker variable.     */    synchronized void startSort() {	if (kicker == null || !kicker.isAlive()) {	    scramble();	    repaint();	    kicker = new Thread(this);	    kicker.start();	}    }    /**     * Here's an inner class that implements all the event handling這里使用一個(gè)內(nèi)部類來(lái)真正實(shí)現(xiàn)該小應(yīng)用程序中所有的事件處理工作     * for this applet.  Wow, this simplifies the code!  I had to     * remove the "private" modifier from the startSort method so      * that this class could use startSort.為了使這個(gè)類能使用startSort方法，這里將私有屬性去掉     */    class ClockStarter extends MouseAdapter {        /**         * The user clicked in the applet. Start the clock!當(dāng)用戶單擊小應(yīng)用程序時(shí)將啟動(dòng)計(jì)時(shí)器         */	public void mouseReleased(MouseEvent e) {	    startSort();	}    }}