Java 1.2 How-To/JavaHowTo.iso/code/ch11.txt

Text File | 1998-12-14 | 12.2 KB | 556 lines

Copy the file GetInetFile.class from the CD-ROM (in the directory for material from Chapter 11)
 to your directory.





Lines.java:

import java.applet.Applet;
import java.awt.*;

/**
 * class LineColors holds 24 color values
 */
class LineColors {

/**
 * color[] array holds the colors to be used
 */
Color color[];

/**
 * class constructor
 * initializes the color array using an arbitrary algorithm
 */
public LineColors () {

    color = new Color[24];
    int i, rgb;

    rgb = 0xff;
    for (i=0; i<24; i+=1) {
        color[i] = new Color (rgb);
        rgb <<= 1;
        if ((rgb & 0x1000000) != 0) {
            rgb |= 1;
            rgb &= 0xffffff;
        }
    }
}
}

/**
 * class describing one line segment
 */
class Segment {

/*
 * x1, y1 - starting coordinates for this segment
 * x2, y2 - ending coordinates for this segment
 * dx1,...dy2 - velocities for the endpoints
 * whichcolor - the current index into color array
 * width, height - width and height of bounding panel
 * LC - instance of LineColors class
 */
double x1, y1, x2, y2;
double dx1, dy1, dx2, dy2;
int whichcolor, width, height;
LineColors LC;

/**
 * class constructor
 * initialize endpoints and velocities to random values
 * @param w - width of bounding panel
 * @param h - height of bounding panel
 * @param c - starting color index
 * @param lc - instance of LineColors class
 */
public Segment (int w, int h, int c, LineColors lc) {

    whichcolor = c;
    width = w;
    height = h;
    LC = lc;
    x1 = (double) w * Math.random ();
    y1 = (double) h * Math.random ();
    x2 = (double) w * Math.random ();
    y2 = (double) h * Math.random ();

    dx1 = 5 - 10 * Math.random ();
    dy1 = 5 - 10 * Math.random ();
    dx2 = 5 - 10 * Math.random ();
    dy2 = 5 - 10 * Math.random ();
}

/*
 * increment color index
 * calculate the next endpoint position for this segment
 */
void compute () {

    whichcolor += 1;
    whichcolor %= 24;

    x1 += dx1;
    y1 += dy1;
    x2 += dx2;
    y2 += dy2;

    if (x1 < 0 || x1 > width) dx1 = -dx1;
    if (y1 < 0 || y1 > height) dy1 = -dy1;
    if (x2 < 0 || x2 > width) dx2 = -dx2;
    if (y2 < 0 || y2 > height) dy2 = -dy2;
}

/**
 * draw the line segment using the current color
 * @param g - destination graphics object
 */
void paint (Graphics g) {

    g.setColor (LC.color [whichcolor]);
    g.drawLine ((int) x1, (int) y1, (int) x2, (int) y2);
}
}

/**
 * The applet/application proper
 */
public class Lines extends Applet {

/*
 * Nlines - number of line segments to be displayed
 * lines - array of instances of Segment class
 * LC - instance of LineColors class
 */
int width,height;
final int NLines = 4;
Segment lines[] = new Segment[NLines];
LineColors LC = new LineColors ();

/**
 * init is called when the applet is loaded
 * save the width and height
 * create instances of Segment class
 */
public void init () {

    setLayout(null);
    width = 300;
    height = 300;
    setSize(width, height);

    int i;
    for (i=0; i<NLines; i+=1)
        lines[i] = new Segment (width, height, (2*i) % 24, LC);
}

/**
 * recompute the next endpoint coordinates for each line
 * invoke paint() method for each line
 * call repaint() to force painting 50ms later
 * @param g - destination graphics object
 */
public void paint (Graphics g) {

    int i;
    for (i=0; i<NLines; i+=1) {
        lines[i].compute ();
        lines[i].paint (g);
    }
    repaint (50);
}








ReadProperties.java:

import java.lang.*;

class ReadProperties {

    public static void main(String[] args) {

        String str;

        try {

            str = System.getProperty("os.name", "not specified");
System.out.println("  OS name: " + str);

            str = System.getProperty("java.version", "not specified");
System.out.println("  JVM Version: " + str);

            str = System.getProperty("user.home", "not specified");
System.out.println("  user.home: " + str);

            str = System.getProperty("java.home", "not specified");
System.out.println("  java.home: " + str);

        } catch (Exception e) {
            System.err.println("Caught exception " + e.toString());
}
    }
}






WarningLetterSet.java:

import java.util.*;

public class WarningLetterSet
{
    public static void main(String args[])
    {
        // Create the lists of failing students
        String[] French = {"Amy", "Jose", "Jeremy", "Alice", "Patrick"};

        String[] Algebra = {"Alan", "Amy", "Jeremy", "Helen", "Alexi"};

        String[] History = {"Adel", "Aaron", "Amy", "James", "Alice"};

        // Create the set to hold the failing students
        Set LettersHome = new HashSet();

        //Add the failing students from each class to the set
        for (int i=0; i< French.length; i++)
            LettersHome.add(French[i]);

        for (int j=0; j< Algebra.length; j++)
            LettersHome.add(Algebra[j]);

        for (int k=0; k< History.length; k++)
            LettersHome.add(History[k]);

        //Print out the number of letters to be sent and the recipient list
        System.out.println(LettersHome.size()+" letters must be sent to: "+LettersHome);

    }//Main
}//Warning Letters







WarningLetterList.java:

import java.util.*;

public class WarningLetterList
{
    public static void main(String args[])
    {
        // Create the lists of failing students
        String[] French = {"Amy", "Jose", "Jeremy", "Alice", "Patrick"};

        String[] Algebra = {"Alan", "Amy", "Jeremy", "Helen", "Alexi"};

        String[] History = {"Adel", "Aaron", "Amy", "James", "Alice"};

        // Create the set to hold the failing students
        List LettersHome = new ArrayList();

        //Add the failing students from each class to the set
        for (int i=0; i< French.length; i++)
            LettersHome.add(French[i]);

        for (int j=0; j< Algebra.length; j++)
            LettersHome.add(Algebra[j]);

        for (int k=0; k< History.length; k++)
            LettersHome.add(History[k]);

        Collections.sort(LettersHome);

        //Print out the number of letters to be sent
// and the recipient list
System.out.println(LettersHome.size()+" letters must be sent to: "+LettersHome);

    }//Main
}//Warning Letters








StudentIDMap.java:

import java.util.*;

public class StudentIDMap
{
    public static void main(String args[])
    {
        // Create the lists of failing students
        String[] SNames = {"Amy", "Jose", "Jeremy", "Alice", "Patrick"};
        String[] ID = {"123456789", "259879864", "988456997", "984876453", "9768696"};

        // Create the set to hold the failing students
        Map IDMap = new HashMap();

        //Add the failing students from each class to the set
        for (int i=0; i< SNames.length; i++)
            IDMap.put(ID[i],SNames[i]);


        //Print out the student list
        System.out.println(IDMap.size()+" Students entered: ");
        System.out.println(IDMap);

    }//Main
}//StudentIDMap







PrintGraphics.java:

import java.awt.*;
import java.awt.event.*;

public class PrintGraphics extends Frame implements ActionListener
{
    PrintCanvas canvas1;

    public PrintGraphics()
    {
        super("PrintGraphics");
        canvas1 = new PrintCanvas();
        add("Center", canvas1);

        Button b = new Button( "Print");
        b.setActionCommand("print");
        b.addActionListener(this);
        add("South",b);

        pack();

    }//constructor

    public void actionPerformed(ActionEvent e)
    {
        String cmd = e.getActionCommand();
        if (cmd.equals("print"))
        {
            PrintJob pjob = getToolkit().getPrintJob(this, "PrintGraphics", null);
if (pjob != null)
            {
                Graphics pg = pjob.getGraphics();

                if (pg != null)
                {
                    canvas1.printAll(pg);
                    pg.dispose();
                }//if
                pjob.end();
            }//if

        }//if

    }//actionPerformed

    public static void main(String args[])
    {
        PrintGraphics test = new PrintGraphics();
        test.addWindowListener(new WindowCloser());
        test.show();

    }
}//class PrintGraphics

class PrintCanvas extends Canvas
{
    public Dimension getPreferredSize()
    {
        return new Dimension(200,200);
    }

    public void paint(Graphics g)
    {
        Rectangle r = getBounds();

        g.setColor(Color.yellow);
        g.fillRect(0,0, r.width, r.height);

        g.setColor(Color.blue);
        g.drawString("Hello, World", 100, 100);

        g.setColor(Color.red);
        g.drawLine(0,100,100,0);
        g.fillOval(135,140,15,15);
    }

}//class PrintCanvas

class WindowCloser extends WindowAdapter
{
    public void windowClosing(WindowEvent e)
    {
        Window win = e.getWindow();
        win.setVisible(false);
        win.dispose();
        System.exit(0);
    }//windowClosing
}//class WindowCloser







TwoDArcs2.java:

import java.awt.*;
import java.awt.event.*;
import java.awt.geom.*;
import java.awt.image.BufferedImage;

public class TwoDArcs2 extends Canvas {

    private int w, h, x, y;
    //Declare the Arc objects
    private Arc2D.Float arc1 = new Arc2D.Float(Arc2D.CHORD);
    private Arc2D.Float arc2 = new Arc2D.Float(Arc2D.OPEN);
    private Arc2D.Float arc3 = new Arc2D.Float(Arc2D.PIE);

    //Buffering support
    private BufferedImage offImg;


    public TwoDArcs2() {
        setBackground(Color.white);
    }


    public void drawArcs(Graphics2D g2)
    {

    //Set the width of the outline

      g2.setStroke(new BasicStroke(5.0f));


     //Draw the chord
      arc1.setFrame(140,30, 67, 46);
      arc1.setAngleStart(45);
      arc1.setAngleExtent(270);
      g2.setColor(Color.blue);
      g2.draw(arc1);
      g2.setColor(Color.gray);
      g2.fill(arc1);
      g2.setColor(Color.black);
      g2.drawString("Arc2D.CHORD", 140, 20);

//Draw the open arc
      arc2.setFrame(140,100, 67, 46);
      arc2.setAngleStart(45);
      arc2.setAngleExtent(270);
      g2.setColor(Color.gray);
      g2.draw(arc2);
      g2.setColor(Color.green);
      g2.fill(arc2);
      g2.setColor(Color.black);
      g2.drawString("Arc2D.OPEN", 140, 90);

//Draw the pie chart
      arc3.setFrame(140, 200, 67, 46);
      arc3.setAngleStart(45);
      arc3.setAngleExtent(270);
      g2.setColor(Color.gray);
      g2.draw(arc3);
      g2.setColor(Color.red);
      g2.fill(arc3);
      g2.setColor(Color.black);
      g2.drawString("Arc2D.PIE",140, 190);
   }


    public Graphics2D createDemoGraphics2D(Graphics g) {
        Graphics2D g2 = null;

        if (offImg == null || offImg.getWidth() != w ||
                        offImg.getHeight() != h) {
            offImg = (BufferedImage) createImage(w, h);
}

        if (offImg != null) {
            g2 = offImg.createGraphics();
            g2.setBackground(getBackground());
        }

        // .. set attributes ..
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING,
                            RenderingHints.VALUE_ANTIALIAS_ON);

        // .. clear canvas ..
        g2.clearRect(0, 0, w, h);

        return g2;
    }


    public void paint(Graphics g) {

        Dimension d = getSize();
        w = d.width;
        h = d.height;
        //System.out.println(w * 2);
        //System.out.println(h);


        if (w <= 0 || h <= 0)
            return;

        Graphics2D g2 = createDemoGraphics2D(g);
        drawArcs(g2);
        g2.dispose();

        if (offImg != null && isShowing())  {
            g.drawImage(offImg, 0, 0, this);
        }

}

    public static void main(String argv[]) {
        final TwoDArcs2 demo = new TwoDArcs2();
        WindowListener l = new WindowAdapter()
        {
            public void windowClosing(WindowEvent e){System.exit(0);}
};
        Frame f = new Frame("Java2D Arcs");
        f.addWindowListener(l);
        f.add("Center", demo);
        f.pack();
        f.setSize(400,300);
        f.show();
    }
}