From awt to swing = classcastexception ?

Hi !
I am trying to move from awt to swing (j2sdk1.4.0_01)
On recompiling with javac, no visible errors, nor when I try to debug with jdb.
However when I try to load the class file, the java console tells me that I have a ClassCastException. Going thru the codes, I cannot see where I have type-casted anything wrong !
Can someone point me in the right direction ?
THX

Hi !
Tried some very simple codes...
import javax.swing.*;
public class TreeExample
public static void main(String args[])
JFrame frame = new JFrame("The Tree");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(250,250);
frame.show();
jdb will run it and display it in an appletviewer
window, but IE and Netscape will report a
ClassCastException...
At this point I think it might be some plug-ins ?The example you gave isn't an applet. Were you trying to run this exact code in a browser or was this just a sample? If you are trying to run this in a browser, it's probably trying to cast your TreeExample class to an Applet, which would explain the ClassCastException.

Similar Messages

Conversion from awt to Swing, colored list widget, and awt update() method

Now that my Interactive Color Wheel program/applet is in Swing, I guess I should continue my previous thread in here from the AWT forum ("list widget with different colors for each list item?"):
* list widget with different colors for each list item?
My current issue involves two canvas (well, JPanel) refresh issues likely linked to double buffering. You can see them by running the following file with "java -jar SIHwheel.jar":
* http://r0k.us/rock/Junk/SIHwheel.jar
[edit add]
(Heh, I just noticed Firefox and Chrome under Windows 7 will allow you to run thie .jar directly from the link. Cool.)
[edit]
If you don't trust me and would rather run it as an applet, use:
* http://r0k.us/rock/Junk/SIHwheel.html
(For some reason the first issue doesn't manifest when running as applet.)
1) The canvas goes "wonky-white" when the user first clicks on the wheel. What is supposed to happen is simply the user sees another dot on the wheel for his new selected color. Forcing a complete redraw via any of the GUI buttons at the bottom sets things right. The canvas behaves itself from then on, at least until minimized or resized, at which point one needs to click a GUI button again. I'll be disabling resizing, but minimizing will still be allowed.
2) A button image, and sometimes toolTip text, from an entirely different JPanel will appear in the ULC (0,0) of my canvas.
Upon first running the new Swing version, I had thought everything was perfect. I soon realized though that my old AWT update() method was never getting called. The desired case when the user clicks somewhere on the wheel is that a new dot appears on his selected color. This usually allows them to see what colors have been viewed before. The old paint(), and now paintComponent(), clear the canvas, erasing all the previous dots.
I soon learned that Swing does not call update(). I had been using it to intercept refresh events where only one of the components on my canvas needing updating. Most usefully, don't redraw the wheel (and forget the dots) when you don't need to. The way I chose to handle this is to slightly modify the update() to a boolean method. I renamed it partialOnly() and call it
at the beginning of paintComponent(). If it returns true, paintComponent() itself returns, and no clearing of the canvas occurs.
Since I first posted about these two issues, I've kludged-in a fix to #1. (The linked .jar file does not contain this kludge, so you can see the issue.) The kludge is included in the following code snippet:
    public void paintComponent(Graphics g)
        Rectangle ulc;
     if (font == null) defineFont(g);
     // handle partial repaints of specific items
     if (partialOnly(g)) return;
        ... // follow with the normal, full-canvas refresh
    private boolean partialOnly(Graphics g)
     boolean     imDone = true;
     if (resized > 0) // this "if { }" clause is my kludge
     {   // should enter on 1 or 2
         imDone = false;
         resized += 1;     // clock thru two forced-full paints
         if (resized > 2) resized = 0;
        if (wedgeOnly)
         putDotOnWheel(g);
            paintWedge(g);
         drawSnake(g);
         drawSatSnake(g);
         updateLumaBars(g);
            wedgeOnly = false;
          else if (wheelOnly)
            wheelOnly = false;
          else
            imDone = false; // was paint() when method was update() in the AWT version
        return(imDone);
    }Forcing two initial full paintComponent()s does whatever magic the double-buffering infrastructure needs to avoid the "wonky-white" problem. This also happens on a minimize; I've disabled resizing other than minimization. Even though it works, I consider it a kludge.
The second issue is not solved. All I can figure is that the double buffers are shared between the two JPanels, and the artifact buttons and toolTips at (0,0) are the result. I tried simply clearing the top twenty lines of the canvas when partialOnly() returns true, but for some reason that causes other canvas artifacting further down. And that was just a second kludge anyway.
Sorry for being so long-winded. What is the right way to avoid these problems?
-- Rich
Edited by: RichF on Oct 15, 2010 8:43 PM

Darryl, I'm not doing any custom double buffering. My goal was to simply replicate the functionality of awt's update() method. And yes, I have started with the Swing tutorial. I believe it was there that I learned update() is not part of the Swing infrastructure.
Problem 1: I don't see the effect you describe (or I just don't understand the description)Piet, were you viewing the program (via the .jar) or the applet (via the .html)? For whatever reason, problem 1 does not manifest itself as an applet, only a program. FTR I'm running JDK/JRE 1.6 under Windows 7. As a program, just click anywhere in the wheel. The whole canvas goes wonky-white, and the wheel doesn't even show. If it happens, you'll understand. ;)
Are you aware that repaint() can have a rectangle argument? And are you aware that the Graphics object has a clip depicting the area that will be affected by painting? You might use these for your partial painting.Yes and yes. Here is an enumeration of most of the update regions:
enum AoI    // areas of interest
    LUMA_SNAKE, GREY_SNAKE, HUEBORHOOD, BULB_LABEL, LUMA_WEDGE,
    LAST_COLOR, BRIGHTNESS_BOX, INFO_BOX, VERSION,
    COLOR_NAME, EXACT_COLOR, LUMA_BUTTON, LUMA_BARS, GUI_INTENSITY,
    QUANTIZATION_ERROR
}That list doesn't even include the large color intensity wedge to the right, nor the color wheel itself. I have a method that will return a Rectangle for any of the AoI's. One problem is that the wheel is a circle, and a containing rectangle will overlap with some of the other AoI's. I could build an infrastructure to handle this mess one clip region at a time, but I think it would add a lot of unnecessary complexity.
I think the bigger picture is that, though it is now updated to Swing, some of the original 1998 design decisions are no longer relevant. Back then I was running Windows 98 on a single-core processor clocked at significantly less than 1 GHz. You could actually watch the canvas update itself. The color wheel alone fills over 1000 arcs, and the color intensity wedge has over 75 update regions of its own. While kind of interesting to watch, it's not 1998 any more. My multi-core processor runs at over 2 GHz, and my graphic card is way, way beyond anything that existed last century. Full canvas updates probably take less than 0.1 sec, and that is with double-buffering!
So, I think you're right. Let the silly paintComponent() do it's thing unhindered. If I want to track old dots on the wheel, keep an array of Points, remembering maybe the last 10. As a final step in the repainting process, decide how many of those old dots to display, and do it.
Thanks, guys, for being a sounding board.
Oh, I'm moving forward on implementing the color list widget. I've already added a 3rd JPanel, which is a column to the left of the main paint canvas. It will contain 3 GUI items:
1) the color list widget itself, initially sorted by name
2) 3 radio buttons allowing user to resort the list by name, hue, or hex
3) a hex-entry JTextField (which is all that is there at this very moment), allowing exact color request
The color list widget will fill most of the column from the top, followed by the radio buttons, with hex-entry at bottom.
For weeks I had in mind that I wanted a pop-up color list widget. Then you shared your ColorList class, and it was so obvious the list should just be there all the time. :)
-- Rich

AWT vs Swing vs Applet

Hi there,
I'm currently writing a chess game and I'm wondering which would be best to use - AWT, Swing or an applet. I read that using Swing in an applet is not advisable as the classes that would need to be downloaded could be quite large and so take quite a long time. I've been writing it using AWT as I feel that it is fairly simple to change it to Swing or to an applet. What are your opinions on this?
Many thanks!

I'm currently writing a chess game and I'm wondering
which would be best to use - AWT, Swing or an applet.Applets are not separate from AWT or Swing. The Applet class forms part of the AWT package, and JApplets are the Swing equivalent. If you were to use an Applet (or JApplet), you would still have to use AWT/Swing classes, such as Panel, Button etc. for the UI for your program, unless you want a mysterious magical grey box ;P
I read that using Swing in an applet is not advisable
as the classes that would need to be downloaded could
be quite large and so take quite a long time. I don't have a lot of experience using the AWT classes, and use the newer Swing ones. I have heard Swing is easier to use, but many browsers do NOT support Swing classes as standard (particularly Internet Explorer), and require the plug-in, which is a fairly hefty download, especially on a dial-up.
I've been writing it using AWT as I feel that it is fairly
simple to change it to Swing or to an applet. What are
your opinions on this?You say you are using AWT at the minute - are you writing the program as an application? If so, then I'm assuming you have the program running in a Frame, and to use the program as an applet, you would want to change your class from extending Frame to extending Applet. There shouldn't be a lot of change to code when adding components, but you will need to implement Applet methods (such as init()).
Just note that in order to use the program on a webpage, it must be an applet. If you want to use the program as an applet, seeing as you have already started by using AWT, you might as well stick with it as you would be putting in effort to convert it into Swing only to restrict the potential audience.
If you want the program to run as an application AND an applet, then the class extending Applet can have a main method, which creates a Frame, before adding a new instance of your applet and calling its init method.

Invoke an awt event from outside the swing application

Is it possible to invoke an awt event triggered from outside the swing app? I am trying to implement a use case where i have to open a new tab in an already running swing app when a user clicks on a browser link.

I have a desktop application that was invoked via webstart. The java webstart process started when the user clicked on a link that downloaded the swing application and now it runs in the clients JVM. Each browser click downloades and launches the application that performs a certain function. Now lets say, the user clicks on another link, then i don't want another java application to be launched. I want the same application that executes the function in lets say a new tab.
Its kind of like you click on a link that somebody sent you in an outlook email. When you click on it and if firefox is already running, the link opens up in a new tab on an already running firefox browser. If firefox was not running, it starts a new firefox process.
Hope this makes sense

How can I create a my own dialog in awt or swings

How can I create a my own dialog in awt or swings instead of JDialog,Joption.
if possible some example.
Thanks in advance
bhaskar

hi,
just use the building blocks of of GUI components and their methods. For examlpe u want to write a Font Dialog box,
use Frame with lists , thers is classes by which u can pick the all fonts installes on ur system. Do appropriate programming to event handlers . On last in event handler of 'OK' button get the selected item from list and assign to wht u want thats all...........

Missing classes from the javax.swing package?

Can anyone throw any light on what appears to be a missing class from the javax.swing package?
When CelsiusConverter.java from The Swing Tutorial (code fragment shown below) is compiled the JFrame class can't be found.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class CelsiusConverter implements ActionListener {
JFrame converterFrame;Despite the package javax.swing being imported, the compiler does not seem to be be able to find the JFrame class.
CelsiusConverter.java:14: Class JFrame not found in type declaration.
JFrame converterFrame;To attempt to solve this issue all the files in jdk1.5.0_02\lib were added to CLASSPATH.
CLASSPATH was set to C:\Program Files\Java\jdk1.5.0_02\lib\dt.jar;C:\Program Files\Java\jdk1.5.0_02\lib\htmlconverter.jar;C:\Program Files\Java\jdk1.5.0_02\lib\jconsole.jar;C:\Program Files\Java\jdk1.5.0_02\lib\tools.jar;C:\Program Files\Java\jdk1.5.0_02\lib;C:\Program Files\Java\jdk1.5.0_02\lib\ir.idl;C:\Program Files\Java\jdk1.5.0_02\lib\jawt.lib;C:\Program Files\Java\jdk1.5.0_02\lib\jvm.lib;C:\Program Files\Java\jdk1.5.0_02\lib\orb.idl;C:\Program Files\Java\jdk1.5.0_02\demo\jfc\SwingApplet\SwingApplet.jar;.;c:\CoreJavaBook

This is extremely strange... If you're sure it's not a problem in your code or with your classpath, the only other thing I can think to suggest is re-downloading / installing java

Lighter Java GUI than awt and swing?

I had recently came across a company website (http://www.bambookit.com) where they developed a java gui library without using awt and swing (seems to what they claim). And on top of that it uses xml to generate the gui components (they call widgets) and the whole library size is only 95kb and supports java 1.1.x and above. Their demos on the applets loads super fast, never know/experience that java applets can actually be this quick. But this confuses me, how is it possible to develop a gui alternative to awt with the basic java classes and no dependency on awt? But since the applets are awt based, it means that they must have some dependencies.
This is an extract from their website (that it seemed they did not use awt)
"Java has a fundamental flaw in its paint thread that made it very difficult to build extremely large applications without getting severe performance and resource penalties (This affects both AWT and Swing based applications). It�s main repaint queue\thread when assigning paint regions to various controls uses the Graphics objects to �clip� them. On a Sun Solaris machine this does not cause any problems, however on a windows machine each Graphics object consumes a system resource/handle, (a limit of around 16,000 exists on Win 95 and Win 98 machines). Each Bitmap image, each font object, each icon consumes a single system resource or handle. If a full repaint is performed on an application containing 1000 controls, it would consume at LEAST 1000 system resource handles. If the application was updated many times a second, lets say 10 times a second, then that equates to 10,000 handles a second. This is not taking into account labels within controls, the various fonts styles and sizes created, the various images that get loaded. This could easily exceed 20,000 system resource requests a second. Bambookit on the other hand utilizes the clip routines and passes along a SINGLE Graphics objects to all its various controls. This alone is a HUGE savings in system resources and performance."
Two questions came to my mind:
1) Is it possible to build applet gui without using awt and swing in java? If so the only way to do is to use JNI calls?
2) Am I wrong in interpreting www.bambookit.com's message that they are not using awt?
Any comments about this?
Regards,
Stanly

They use AWT as basis for their drawing-layer, as any other lightweight toolkits too.
If you just want a very fast & light alternative to swing/awt have a look at www.lwvcl.com !
I use it for a large applet-applikation that has to be java-1.1 compatible. It was a horor when using AWT which was implemented different over all JVMs available and very slow (although native widgets were used).
With lwvcl (which has only 150kB!) I can use state of the art applets that work very fast on modern jvms like 1.4, give me the ability to compile my applikation to native code using GCJ (using the swt-prt of the library) or distribute it to old-school 1.1 browser where it also runs quite fine...
Its free for GPL and very cheap for commercial use.
lg Clemens

Help Plz! AWT to Swing Conversion

Hey everyone, I'm new to java and trying to convert this AWT program to Swing, I got no errors, the menu shows but they dont work !! Could somebody please help me? thanks alot!
Current Under-Construction Code: (no errors)
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
class zipaint extends JFrame implements ActionListener,      ItemListener,
MouseListener, MouseMotionListener, WindowListener {
static final int WIDTH = 800;     // Sketch pad width
static final int HEIGHT = 600;     // Sketch pad height
int upperLeftX, upperLeftY;     // Rectangle upper left corner coords.
int width, height;          // Rectangle size
int x1, y1, x2, y2, x3, y3, x4, y4; // Point coords.
boolean fillFlag = false; //default filling option is empty
boolean eraseFlag = false; //default rubber is off
String drawColor = new String("black"); //default drawing colour is black
String drawShape = new String("brush"); //default drawing option is brush
Image background; //declear image for open option
private FileDialog selectFile = new FileDialog( this,
"Select background (.gif .jpg)",
FileDialog.LOAD );
// Help
String helpText = "Draw allows you to sketch different plane shapes over a " +
"predefined area.\n" + "A shape may be eother filled or in outline, " +
"and in one of eight different colours.\n\n" + "The position of the " +
"mouse on the screen is recorded in the bottom left-hand corner of the " +
"drawing area. The choice of colour and shape are disoplayed also in the " +
"left-habnd corner of the drawing area.\n\n" + "The size of a shape is " +
"determined by the mouse being dragged to the final position and " +
"released. The first click of the mouse will generate a reference dot on " +
"the screen. This dot will disapear after the mouse button is released.\n\n" +
"Both the square and the circle only use the distance measured along the " +
"horizontal axis when determining the size of a shape.\n\n" + "Upon " +
"selecting erase, press the mouse button, and move the mouse over the " +
"area to be erased. releasing the mouse button will deactivate erasure.\n\n" +
"To erase this text area choose clearpad from the TOOLS menu.\n\n";
// Components
JTextField color = new JTextField();
JTextField shape = new JTextField();
JTextField position = new JTextField();
CheckboxGroup fillOutline = new CheckboxGroup();
JTextArea info = new JTextArea(helpText,0,0/*,JTextArea.JSCROLLBARS_VERTICAL_ONLY*/);
JFrame about = new JFrame("About Zi Paint Shop");
// Menues
String[] fileNames = {"Open","Save","Save as","Exit"};
String[] colorNames = {"black","blue","cyan","gray","green","magenta","red","white","yellow"};
String[] shapeNames = {"brush","line","square","rectangle","circle","ellipse"};
String[] toolNames = {"erase","clearpad"};
String[] helpNames = {"Help","about"};
public zipaint(String heading) {
super(heading);
getContentPane().setBackground(Color.white);
getContentPane().setLayout(null);
/* Initialise components */
initialiseTextFields();
initializeMenuComponents();
initializeRadioButtons();
addWindowListener(this);
addMouseListener(this);
addMouseMotionListener(this);
/* Initialise Text Fields */
private void initialiseTextFields() {
// Add text field to show colour of figure
color.setLocation(5,490);
color.setSize(80,30);
color.setBackground(Color.white);
color.setText(drawColor);
getContentPane().add(color);
// Add text field to show shape of figure
shape.setLocation(5,525);
shape.setSize(80,30);
shape.setBackground(Color.white);
shape.setText(drawShape);
getContentPane().add(shape);
// Add text field to show position of mouse
position.setLocation(5,560);
position.setSize(80,30);
position.setBackground(Color.white);
getContentPane().add(position);
// Set up text field for help
info.setLocation(150,250);
info.setSize(500,100);
info.setBackground(Color.white);
info.setEditable(false);
private void initializeMenuComponents() {
// Create menu bar
JMenuBar bar = new JMenuBar();
// Add colurs menu
JMenu files = new JMenu("Files");
for(int index=0;index < fileNames.length;index++)
files.add(fileNames[index]);
bar.add(files);
files.addActionListener(this);
// Add colurs menu
JMenu colors = new JMenu("COLORS");
for(int index=0;index < colorNames.length;index++)
colors.add(colorNames[index]);
bar.add(colors);
colors.addActionListener(this);
// Add shapes menu
JMenu shapes = new JMenu("SHAPES");
for(int index=0;index < shapeNames.length;index++)
shapes.add(shapeNames[index]);
bar.add(shapes);
shapes.addActionListener(this);
// Add tools menu
JMenu tools = new JMenu("TOOLS");
for(int index=0;index < toolNames.length;index++)
tools.add(toolNames[index]);
bar.add(tools);
tools.addActionListener(this);
// Add help menu
JMenu help = new JMenu("HELP");
for(int index=0;index < helpNames.length;index++)
help.add(helpNames[index]);
bar.add(help);
help.addActionListener(this);
// Set up menu bar
setJMenuBar(bar);
/* Initilalise Radio Buttons */
private void initializeRadioButtons() {
// Define checkbox
Checkbox fill = new Checkbox("fill",fillOutline,false);
Checkbox outline = new Checkbox("outline",fillOutline,true);
// Fill buttom
fill.setLocation(5,455);
fill.setSize(80,30);
getContentPane().add(fill);
fill.addItemListener(this);
// Outline button
outline.setLocation(5,420);
outline.setSize(80,30);
getContentPane().add(outline);
outline.addItemListener(this);
/* Action performed. Detects which item has been selected from a menu */
public void actionPerformed(ActionEvent e) {
Graphics g = getGraphics();
String source = e.getActionCommand();
// Identify chosen colour if any
for (int index=0;index < colorNames.length;index++) {
if (source.equals(colorNames[index])) {
drawColor = colorNames[index];
color.setText(drawColor);
return;
// Identify chosen shape if any
for (int index=0;index < shapeNames.length;index++) {
if (source.equals(shapeNames[index])) {
drawShape = shapeNames[index];
shape.setText(drawShape);
return;
// Identify chosen tools if any
if (source.equals("erase")) {
eraseFlag= true;
return;
else {
if (source.equals("clearpad")) {
remove(info);
g.clearRect(0,0,800,600);
return;
if (source.equals("Open")) {
selectFile.setVisible( true );
if( selectFile.getFile() != null )
String fileLocation = selectFile.getDirectory() + selectFile.getFile();
background = Toolkit.getDefaultToolkit().getImage(fileLocation);
paint(getGraphics());
if (source.equals("Exit")) {
System.exit( 0 );
// Identify chosen help
if (source.equals("Help")) {
getContentPane().add(info);
return;
if (source.equals("about")) {
displayAboutWindow(about);
return;
public void paint(Graphics g)
super.paint(g);
if(background != null)
Graphics gc = getGraphics();
gc.drawImage( background, 0, 0, this.getWidth(), this.getHeight(), this);
/* Dispaly About Window: Shows iformation aboutb Draw programme in
separate window */
private void displayAboutWindow(JFrame about) {
about.setLocation(300,300);
about.setSize(350,160);
about.setBackground(Color.cyan);
about.setFont(new Font("Serif",Font.ITALIC,14));
about.setLayout(new FlowLayout(FlowLayout.LEFT));
about.add(new Label("Author: Zi Feng Yao"));
about.add(new Label("Title: Zi Paint Shop"));
about.add(new Label("Version: 1.0"));
about.setVisible(true);
about.addWindowListener(this);
// ----------------------- ITEM LISTENERS -------------------
/* Item state changed: detect radio button presses. */
public void itemStateChanged(ItemEvent event) {
if (event.getItem() == "fill") fillFlag=true;
else if (event.getItem() == "outline") fillFlag=false;
// ---------------------- MOUSE LISTENERS -------------------
/* Blank mouse listener methods */
public void mouseClicked(MouseEvent event) {}
public void mouseEntered(MouseEvent event) {}
public void mouseExited(MouseEvent event) {}
/* Mouse pressed: Get start coordinates */
public void mousePressed(MouseEvent event) {
// Cannot draw if erase flag switched on.
if (eraseFlag) return;
// Else set parameters to 0 and proceed
upperLeftX=0;
upperLeftY=0;
width=0;
height=0;
x1=event.getX();
y1=event.getY();
x3=event.getX();
y3=event.getY();
Graphics g = getGraphics();
displayMouseCoordinates(x1,y1);
public void mouseReleased(MouseEvent event) {
Graphics g = getGraphics();
// Get and display mouse coordinates
x2=event.getX();
y2=event.getY();
displayMouseCoordinates(x2,y2);
// If erase flag set to true reset to false
if (eraseFlag) {
eraseFlag = false;
return;
// Else draw shape
selectColor(g);
if (drawShape.equals("line")) g.drawLine(x1,y1,x2,y2);
else if (drawShape.equals("brush"));
else drawClosedShape(drawShape,g);
/* Display Mouse Coordinates */
private void displayMouseCoordinates(int x, int y) {
position.setText("[" + String.valueOf(x) + "," + String.valueOf(y) + "]");
/* Select colour */
private void selectColor(Graphics g) {
for (int index=0;index < colorNames.length;index++) {
if (drawColor.equals(colorNames[index])) {
switch(index) {
case 0: g.setColor(Color.black);break;
case 1: g.setColor(Color.blue);break;
case 2: g.setColor(Color.cyan);break;
case 3: g.setColor(Color.gray);break;
case 4: g.setColor(Color.green);break;
case 5: g.setColor(Color.magenta);break;
case 6: g.setColor(Color.red);break;
case 7: g.setColor(Color.white);break;
default: g.setColor(Color.yellow);
/* Draw closed shape */
private void drawClosedShape(String shape,Graphics g) {
// Calculate correct parameters for shape
upperLeftX = Math.min(x1,x2);
upperLeftY = Math.min(y1,y2);
width = Math.abs(x1-x2);
height = Math.abs(y1-y2);
// Draw appropriate shape
if (shape.equals("square")) {
if (fillFlag) g.fillRect(upperLeftX,upperLeftY,width,width);
else g.drawRect(upperLeftX,upperLeftY,width,width);
else {
if (shape.equals("rectangle")) {
if (fillFlag) g.fillRect(upperLeftX,upperLeftY,width,height);
else g.drawRect(upperLeftX,upperLeftY,width,height);
else {
if (shape.equals("circle")) {
if (fillFlag) g.fillOval(upperLeftX,upperLeftY,width,width);
else g.drawOval(upperLeftX,upperLeftY,width,width);
else {
if (fillFlag) g.fillOval(upperLeftX,upperLeftY,width,height);
else g.drawOval(upperLeftX,upperLeftY,width,height);
/* Mouse moved */
public void mouseMoved(MouseEvent event) {
displayMouseCoordinates(event.getX(),event.getY());
/* Mouse dragged */
public void mouseDragged(MouseEvent event) {
Graphics g = getGraphics();
x2=event.getX();
y2=event.getY();
x4=event.getX();
y4=event.getY();
displayMouseCoordinates(x1,y1);
if (eraseFlag) g.clearRect(x2,y2,10,10);
else {
selectColor(g);
if(drawShape.equals("brush")) g.drawLine(x3,y3,x4,y4);
x3 = x4;
y3 = y4;
// ---------------------- WINDOW LISTENERS -------------------
/* Blank methods for window listener */
public void windowClosed(WindowEvent event) {}
public void windowDeiconified(WindowEvent event) {}
public void windowIconified(WindowEvent event) {}
public void windowActivated(WindowEvent event) {}
public void windowDeactivated(WindowEvent event) {}
public void windowOpened(WindowEvent event) {}
/* Window Closing */
public void windowClosing(WindowEvent event) {
if (event.getWindow() == about) {
about.dispose();
return;
else System.exit(0);
Code End
Thanks again!
class ziapp {
/* Main method */
public static void main(String[] args) {
zipaint screen = new zipaint("Zi Paint Shop");
screen.setSize(zipaint.WIDTH,zipaint.HEIGHT);
screen.setVisible(true);

First of all use the [url http://forum.java.sun.com/features.jsp#Formatting]Formatting Tags when posting code to the forum. I'm sure you don't code with every line left justified so we don't want to read unformatted code either.
Hey everyone, I'm new to java and trying to convert this AWT program to SwingInstead of converting the whole program, start with something small, understand how it works and then convert a different part of the program. You can start by reading this section from the Swing tutorial on [url http://java.sun.com/docs/books/tutorial/uiswing/components/menu.html]How to Use Menus.
From a quick glance of your code it looks like you are not adding an ActionListener to your JMenuItems. You are adding them to the JMenu.
Other observations:
1) Don't mix AWT with Swing components. You are still using CheckBox
2) Don't override paint(). When using Swing you should override paintComponent();
3) Use LayoutManagers. Using a null layout does not allow for easy maintenance of the gui. Right now you are using 800 x 600 as your screen size. Most people are probably using at least 1024 x 768 screen sizes. When using LayoutManagers you would suggest component sizes by using setPreferredSize(), not setSize().

Learn AWT before Swing?

I have zero practical knowledge of Java GUI programming.
Swing sits on top of AWT. Swing is easier than AWT. Yet, so as to understand Swing, and to be able to do things Swing might not be able to do, I am inclined to first only use AWT. Build a base on which to learn Swing.
A counter argument would be, in my opinion, C vs. C++. While C++ sits on top of C, I don't see any benefit to learning pure C before C++. Further, I don't want things to be too difficult before making them easier regarding GUIs.
Should the progression be: AWT then Swing? Swing then AWT then Swing? just Swing, and learn AWT if ever needed?

I agree with the others, just learn swing and the parts of awt you need will just come along.
But I want to add that using a GUI generator to create swing for you is very tempting, especially at first, but is the worst thing you can do to handicap yourself. I know you didn't mention them, so this is sort of comming from left field, but just saying avoid them until you really know swing.
Also, how can you not see a benefit in learning C before C++? True C++ (even if not always practiced) is object oriented whereas true C is procedural. While OO programming is generally better, it is beneficial to understand procedural programming as well, and knowing both will only make you better as a programmer. But even more important is by never learning true C one never has a chance to learn just how powerful pointers are. Pointers are difficult to get your head around, but they are extreemly usefull, if you are one of the few rare people who can use them correctly and unlock their true power.
Just Saying.
JSG

Catching events on Desktop , without using any AWT or Swing components.

How can I catch events(for eg: mouse clicks) on the Desktop? I do not want to use any AWT or Swing components in my application.
Also, i want to get events even some other java/non-java application windows are visible on desktop, as long as my application is running.

Myrequirement is to capture all AWT events, regardless of on which component its being happened.
I mean I have to capture events outside the current running application (on desktop and any other java/no-java appliation windows also).
I couldn't find any other forum which discusses about event handling.
This is part of my app. other end extensively uses awt.

Why is HeadlessException explicitly thrown in AWT and swing?

Hi there,
I just noticed that HeadlessException is explicitly thrown in some of the constructors in AWT and swing components since J2SE 1.4.
Given that it's a RuntimeException (unchecked) it doesn't need to be included in the throws clause of the method or constructor.
There also seems to be inconsistent application of it and inconsistent documentation in the javadoc comments.
Is this a work in progress or did some refactoring go wrong?

Most probably IE security settings preventing the js file to be executed. Replied in your other post:
Unable to get property 'style' of undefined or null reference in sp.ui.dialog.debug.js
Thanks,
Sohel Rana
http://ranaictiu-technicalblog.blogspot.com

AWT vs SWING and more

1)Though the components used in awt and swing are similar what is the need for two seperate packages ?
and
2)what is the main usage of "getContentPane()" ?
3)why do we use an appletviewer for executing applets provided the OS is Windows NT ..

1)Though the components used in awt and swing are
similar what is the need for two seperate packages ?AWT uses the native (heavyweight) components of the underlying Operating System. Actually a common (and small) subset of the provided components.
In Swing the components a lightweight, there's no native component behind them, the components are painted by pure java code (sometimes sophisticated components). The swing applications thus can look and feel the same on all platforms.
2)what is the main usage of "getContentPane()" ?When using swing you shouldn't add lightweight components to the window subclasses, only to the content pane.
3)why do we use an appletviewer for executing applets
provided the OS is Windows NT ..Did not understand.
Kurta

Difference between awt ang Swing Interview Question n other Question

hi every one i use to think that i know java atlest so much that i can crack a lolcal comp interview but ........................
i ansered few Question but was speachlees when was asked few of this i do not remember all of them
1] difference between awt and swing.
2]System.out.println();
System is a class out is a variable so who come a variable calling a method.
3]are constractor inherateed in java.

1] difference between awt and swing.AWT is based on an abstraction of platform-specific, heavy-weight components. Swing is written entirely in java.
>
2]System.out.println();
System is a class out is a variable so who come a
variable calling a method.Do you mean how come?
In that case, the answer is simple: Because out is a variable, it can be redirected/compared against, etc much easier
3]are constractor inherateed in java.Kind of a trick question, as the answer is yes and no. Constructors are not inherited, but every constructor in the subclass must call one and exactly one constructor of the superclass

Database Connection to AWT and Swings

How do we provide database connection to AWT and swing components?
Is their any possibility to create database connection?
Thanks in advance

Just create an independent DAO class which does all the database/JDBC tasks.
Then use this DAO class as you use every other class in your AWT/Swing application.

Running JUnit tests from AWT Event Quene

Anyone know how to run JUnit tests from the AWT Event Queue? JFCUnit is overkill; I'm just looking for a TestRunner that runs on a different thread. I can delve into the JUnit documentation but, with luck, someone who's been through this before can spare me the trouble. Also, anyone else get a server error when searching for "JUnit event dispatch" on this forum?

JUnit 3 version:
import java.util.concurrent.atomic.AtomicReference;
import javax.swing.SwingUtilities;
import junit.framework.TestCase;
public abstract class EDTTestCase extends TestCase {
     * Overriding this method guarantees that setUp(), tearDown(), and all
     * tests run on the EDT.
    @Override
    public void runBare() throws Throwable {
        final AtomicReference<Throwable> problem = new AtomicReference<Throwable>();
        if (!SwingUtilities.isEventDispatchThread()) {
            SwingUtilities.invokeAndWait(new Runnable() {
                public void run() {
                    try {
                        runBare();
                    catch (Throwable throwable) {
                        problem.set(throwable);
            if (problem.get() != null) {
                throw problem.get();
        else {
            super.runBare();
}

From awt to swing = classcastexception ?

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