put an applet into a web page

Hi, my codes works well in NetBeans as an applet, but why no appearance in a html.

One thing I must mention is I create my code that works both as an applet and as a stand-alone application.
I have three class: Combox.java ,Drawing.java and TextCell.java.
The code structure looks like
Thanks for any help.

The HTML tag is called "applet", not "Japplet".

I have changed, but only a retcange frame showed, no any components.

Are there any messages in the browser status bar, or the Java Console?

No, but in my class "TestCell", File I/O indeed exists.
Is the reason or not?

Thanks

One thing I forget is:
Press Spacebar or Enter to activate this control
activate the control is to click inside the border of the applet.
But I click anywhere, nothing.

Do applets work in general, e.g. the ones on this page? Can you try it with a different browser than IE?

All the examples works well except mine.
I tried them in IE and Firefox.
Dawn!

Does the applet contain code that actually shows something? I'm asking because the code you posted does not seem to do anything graphical.

ok,first thanks for your nice reply.Then my code is:

import java.io.*;
import java.util.List;
import java.util.ArrayList;
import java.util.LinkedList;
import java.util.ListIterator;
import java.util.Scanner;
 
import java.awt.Font;
import java.awt.Color;
import java.awt.Graphics;
import java.awt.BasicStroke;
import java.awt.GradientPaint;
import java.awt.geom.GeneralPath;
 
import java.awt.AlphaComposite;
import java.awt.Composite;
import java.awt.geom.*;
 
import java.awt.*;
import java.awt.BorderLayout;
import javax.swing.*;
 
import java.util.Hashtable;
import java.awt.event.*;
import javax.swing.event.*;
import java.applet.Applet;
public class Combox extends JApplet
{
private Drawing drawing;
private Container Panel;
public void init()
{
Panel = getContentPane();
                drawing = new Drawing();
                Panel.add(drawing,"Center");
}
}
 
 class Drawing extends JPanel 
{
    final int TRANSITION = 100; // Transition x,y coordinates of cells.
    private double x1, y1, x2, y2; // to plot lines from (x1,y1) to (x2,y2)
 
    private double xCells[][]; // Every cell's points's x coordinates array
    private double yCells[][]; // Every cell's points's y coordinates array
    private double rgb[][]; // Color red, green, blue for each point in each cell
    
    private double red[][];
    private double green[][];
    private double blue[][];
    private String energyId[];
    
    private int sideId;
    private int sidesTotalNumber; // Total sides number for all cells
    private int rgbLength; // Total rgb color group number for all cells at each point
    private int cellsPointsNumber[]; // point numbers of each cell.(each cell has how many points)
    private int numberofCells;
    private int numberofsets;
    private int id; //PlotEnergyId
    private double lineWidth;
    private float a = 1;
    
    double scale = 1.0;
    private String currentPattern;
    
    private JSlider dJSlider;
    private JComboBox comb;
    private JComboBox alfa;
    private String af[] = {"0","0.5","1"};
    public void SliderFrame()
    {
        int min = 1, max = 16, inc = 5;
        dJSlider = new JSlider(min, max, 6);
        
        dJSlider.setMajorTickSpacing(5);
        dJSlider.setMinorTickSpacing(1);
        dJSlider.setSnapToTicks(true);
        dJSlider.setLabelTable(getLabelTable(min, max, inc));
        dJSlider.setPaintTicks(true);
        dJSlider.setPaintLabels(true);
        dJSlider.addChangeListener(
                new ChangeListener() // anonymous inner class
                // handle change in slider value
               {
                    public void stateChanged(ChangeEvent e)
                    {
                       int value = ((JSlider)e.getSource()).getValue();
                       scale = (value+4)/10.0;
                    }
                }
        );     
                    add(dJSlider,BorderLayout.EAST); // ADD Slider
    }
    
     private Hashtable getLabelTable(int min, int max, int inc) {
        Hashtable<Integer, JLabel> table = new Hashtable<Integer, JLabel>();
        for(int j = min; j <= max; j+=inc) {
            String s = String.format("%.1f", (j+4)/10.0);
            table.put(Integer.valueOf(j), new JLabel(s));
        }
        return table;
    }
 
    public void paintComponent(Graphics g)
    {
            super.paintComponent( g ); // call superclass's paint method
            this.setBackground( Color.WHITE );
            Graphics2D g2d = (Graphics2D)g; // cast g to Graphics 2D
               
            getDrawingData();SliderFrame();
            ComboBoxDemo();
                g2d.setComposite(makeComposite(a));
            drawPolygon(g2d);  
//            Composite originalComposite = g2d.getComposite();
//            g2d.setColor(Color.GRAY);
 
            drawSides(g2d);
 
 
//              g2d.setComposite(originalComposite);
}
   // end method paintComponent
   
    private AlphaComposite makeComposite(float alpha) 
    {
          int type = AlphaComposite.SRC_OVER;
          return(AlphaComposite.getInstance(type, alpha));
    }
         
    public void getDrawingData()
    {
          TestCell p = new TestCell();
          p.cellData();
          p.energyId();
          p.rgbs();
          xCells = p.getxCells();
          yCells = p.getyCells();
 
          sidesTotalNumber = p.getsidesTotalNumber();
 //         rgb = p.getrgb();
          red = p.getred();
          green = p.getgreen();
          blue  = p.getblue();
          
          energyId = p.getenergyId();
          
          rgbLength = p.getrgbLength();
          cellsPointsNumber = p.getcellsPointsNumber();//array: each cell has how many points
          numberofCells = p.getnumberofCells();
          numberofsets  = p.getnumberofsets();
 
            for(int i = 0; i < numberofCells; i++)
            { 
              for(int j = 0; j<cellsPointsNumber[i]; j++)
              {
                  xCells[i][j] = (xCells[i][j])*scale+TRANSITION;
                  yCells[i][j] = (yCells[i][j])*scale+TRANSITION;
              }
          }
       }
    
       public void drawSides(Graphics2D g2d)
       {
           g2d.setColor(Color.GRAY);
            g2d.setStroke(new BasicStroke((float)lineWidth));
            for (int i = 0; i<numberofCells; i++)
            {
                for (int j = 0; j<cellsPointsNumber[i]-1; j++)
                {  
                    x1 = xCells[i][j];
                    y1 = yCells[i][j];
                    x2 = xCells[i][j+1];
                    y2 = yCells[i][j+1];
                    Line2D line = new Line2D.Double(x1,y1,x2,y2);
                    g2d.draw(line);// draw Sidess here
                } 
             }
            }
       
       public void drawPolygon(Graphics2D g2d)
       {
             for (int i = 0; i<numberofCells; i++)
             {
                Polygon poly = new Polygon();
                float r  = (float)red[i][id]; 
                 // red for ith cell,id is from 0 to numberofsets-1
                 // if id=0, means "Mixture"
                float g  = (float)green[i][id]; // green for ith cell
                float b  = (float)blue[i][id]; // blue for ith cell
                List<Integer> xList = new ArrayList<Integer>(); 
                List<Integer> yList = new ArrayList<Integer>();
                for (int j = 0; j<cellsPointsNumber[i]; j++)
                {  
                    xList.add((int)(xCells[i][j]));
                    yList.add((int)(yCells[i][j]));
                } 
                Integer[] x = xList.toArray(new Integer[xList.size()]);
                Integer[] y = yList.toArray(new Integer[yList.size()]);
                for (int s = 0; s<xList.size(); s++)
                {
                    poly.addPoint(x[s],y[s]);
                }
                g2d.setColor(new Color(r, g, b));// transparent drawing
                  g2d.fillPolygon(poly);
              }  
       }
    
    public void ComboBoxDemo() {
        GridLayout Layout1 = new GridLayout(2,1);
        currentPattern = energyId[0];
        comb = new JComboBox(energyId);
        JPanel cPanel = new JPanel();
        cPanel.setLayout(Layout1);
        comb.setEditable(false);
//        comb.addActionListener(this);
        comb.setForeground (Color.red);
        comb.setBackground (Color.yellow);
    
        comb.setAlignmentX(Component.LEFT_ALIGNMENT);
        comb.addActionListener(
                new ActionListener() // anonymous inner class
                {
                    public void actionPerformed(ActionEvent e)
                    {
                       JComboBox cb = (JComboBox)e.getSource();
                       id = cb.getSelectedIndex();
                    }
                }
        );
        
        alfa = new JComboBox(af);
        alfa.setEditable(false);
        alfa.setForeground(Color.BLUE);
        alfa.setBackground(Color.GREEN);
        alfa.setAlignmentX(Component.LEFT_ALIGNMENT);
        alfa.addActionListener(
                new ActionListener() // anonymous inner class
                {
                    public void actionPerformed(ActionEvent e)
                    {
                       JComboBox cc = (JComboBox)e.getSource();
                       a = (float)(cc.getSelectedIndex()/2.0);
//                      repaint();
                    }
                }
        );
         cPanel.add(comb);
         cPanel.add(alfa);
        add(cPanel,BorderLayout.WEST);
        setBorder(BorderFactory.createEmptyBorder(10,10,10,10));
 } 
            public static void main(String[] args)
            {
            JFrame appletFrame = new JFrame("My Applet");
            Applet theApplet = new Combox();
            appletFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
            appletFrame.setSize(800,800);
            appletFrame.add(theApplet,"Center");
            theApplet.init();
            appletFrame.setVisible(true);
            }
} // end class Drawing

The error from Java console is

Java Plug-in 1.6.0_01
Using JRE version 1.6.0_01 Java HotSpot(TM) Client VM
User home directory = C:\Documents and Settings\2z7

----------------------------------------------------
c:   clear console window
f:   finalize objects on finalization queue
g:   garbage collect
h:   display this help message
l:   dump classloader list
m:   print memory usage
o:   trigger logging
p:   reload proxy configuration
q:   hide console
r:   reload policy configuration
s:   dump system and deployment properties
t:   dump thread list
v:   dump thread stack
x:   clear classloader cache
0-5: set trace level to <n>
----------------------------------------------------
 
java.lang.reflect.InvocationTargetException
at java.awt.EventQueue.invokeAndWait(Unknown Source)
at javax.swing.SwingUtilities.invokeAndWait(Unknown Source)
at Combox.init(Combox.java:57)
at sun.applet.AppletPanel.run(Unknown Source)
at java.lang.Thread.run(Unknown Source)
Caused by: java.security.AccessControlException: access denied (java.util.PropertyPermission user.dir read)
at java.security.AccessControlContext.checkPermission(Unknown Source)
at java.security.AccessController.checkPermission(Unknown Source)
at java.lang.SecurityManager.checkPermission(Unknown Source)
at java.lang.SecurityManager.checkPropertyAccess(Unknown Source)
at java.lang.System.getProperty(Unknown Source)
at java.io.Win32FileSystem.getUserPath(Unknown Source)
at java.io.Win32FileSystem.resolve(Unknown Source)
at java.io.File.getAbsolutePath(Unknown Source)
at sun.awt.shell.Win32ShellFolder2.<init>(Unknown Source)
at sun.awt.shell.Win32ShellFolder2.listFiles(Unknown Source)
at sun.awt.shell.ShellFolder.listFiles(Unknown Source)
at sun.awt.shell.Win32ShellFolderManager2.get(Unknown Source)
at sun.awt.shell.ShellFolder.get(Unknown Source)
at javax.swing.plaf.metal.MetalFileChooserUI.updateUseShellFolder(Unknown Source)
at javax.swing.plaf.metal.MetalFileChooserUI.installComponents(Unknown Source)
at javax.swing.plaf.basic.BasicFileChooserUI.installUI(Unknown Source)
at javax.swing.plaf.metal.MetalFileChooserUI.installUI(Unknown Source)
at javax.swing.JComponent.setUI(Unknown Source)
at javax.swing.JFileChooser.updateUI(Unknown Source)
at javax.swing.JFileChooser.setup(Unknown Source)
at javax.swing.JFileChooser.<init>(Unknown Source)
at javax.swing.JFileChooser.<init>(Unknown Source)
at FileSelection.getFile(FileSelection.java:10)
at Combox.initComponents(Combox.java:70)
at Combox.access$000(Combox.java:28)
at Combox$1.run(Combox.java:59)
at java.awt.event.InvocationEvent.dispatch(Unknown Source)
at java.awt.EventQueue.dispatchEvent(Unknown Source)
at java.awt.EventDispatchThread.pumpOneEventForFilters(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForFilter(Unknown Source)
at java.awt.EventDispatchThread.pumpEventsForHierarchy(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.pumpEvents(Unknown Source)
at java.awt.EventDispatchThread.run(Unknown Source)

Applets are not allowed to do file I/O, unless they are signed, or the local security policy altered. That's what's causing this exception. See HowCanAnAppletReadFilesOnTheLocalFileSystem for more details.

yes,I am doing a self-signed certificate, I followed an example on the web.
But I got wrong at some step. Any help, thanks.
Where is the file migsuncert.crt located?

Originally posted by Hui Zhao:
Where is the file migsuncert.crt located?

C:\Program Files\Java\jdk1.6.0_01\bin>keytool -export -alias migkey -file migsuncert.crt
Enter keystore password:
keytool error: java.io.FileNotFoundException: migsuncert.crt (Access is denied)

The filename is used for the certificate file you're trying to export to; it doesn't exist yet. Does the account you're using possibly not have write permissions for that directory? That's another reason for that exception to happen.

I signed successfully in another machine.
And I follow the instructions in the book "Java Cookbook".
You can now sign the JAR file with your test certificate:

The jarsigner tool updates the META-INF directory of your JAR file to
contain certificate information and digital signatures for each entry in the archive.
Now I have two questions.
1)What is meant by the term "META-INF" directory?
2)Because my applet contains File I/O, after this step can I run my applet?

What is meant by the term "META-INF" directory?

Jar files contain a META-INF directory which in most cases contains just a single file: the manifest. In it you'll find various pieces of meta information about the jar file, including information about its signature. That's why it is updated if the jar file is signed. The jar file specification has more details on this.

Because my applet contains File I/O, after this step can I run my applet?

It should run. Have you tried it?

okay,it works well.
One more question:why the height is 0, how can I set it?

Thank you very much.