AWT vs SWING vs JAVA 2D vs JFC
Hi,
can you please describe or show me the path to find the difference
among 4. (mentioned in subject line)
The basic difference i know, what i want is how to decide when to use
what?
In my view, awt is used no where these days.
swing and Java 2D (what is this?) are used mostly but which to choose
for my application, how to decide? and What is JFC all about?
sometimes it becomes very confusing.
Can anyone throw some light on these terms.
- Thanks
Azodious
Edited by: Azodious on Jan 26, 2008 5:23 AM
Azodious wrote:
i didn't search on Google because here experts have some special answers. by special answers i mean less words but exact answer. with a lot of learning.
i am expectng those kind of answers.You may be waiting a long time. Your question is very broad, very general, and most experts would likely refer you to reference sources.
This may be a language thing, but to say you "expect" answers is awfully presumptuous.
otherwise i'd to go through all those many pages again and again to grasp a simple but conceptual thing.Have at it.
Similar Messages
-
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,
StanlyThey 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 -
Are JFC Swing and java Swing both different?
Thanks.Nope. Swing is Swing.
http://java.sun.com/docs/books/tutorial/uiswing/14start/about.html -
Java.awt.Container.add(Container.java:345) how can i handle this
dear all,
i want to design an outlook for a chat applet. but this seems to tough as i am getting a run time error
my code is:
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.net.*;
import java.io.*;
import javax.swing.*;
* the import that are required for this class
public class outer extends Frame //implements ActionListener, Runnable
private TextField txtusername,txtpassword,txtroomname;
private Label lblusername,lblpassword,lblroomname,lbllistofrooms;
Button okBtn,exitBut;
Color backColor=null,btnBackClr=null,btnForeClr=null;
String[] roomsavailable = {" one ", " two ", " three", " four"};
private JList rooms = new JList(roomsavailable);
/** the costructor*/
public outer()
{ // super(st);
backColor=new Color(200,200,255);
btnBackClr=new Color(225,240,255);
btnForeClr=new Color(205,205,205);
setBackground(backColor);
setLayout(null);
lblusername = new Label("Username");
lblusername.reshape(insets().left+5,insets().top+10,60,20);
add(lblusername);
txtusername=new TextField();
txtusername.reshape(insets().left+75,insets().top+10,60,20);
add(txtusername);
lblpassword = new Label("Password");
lblpassword.reshape(insets().left+5,insets().top+30,60,20);
add(lblpassword);
txtpassword=new TextField();
txtpassword.reshape(insets().left+75,insets().top+30,60,20);
add(txtpassword);
lblroomname = new Label("Select Room");
lblroomname.reshape(insets().left+5,insets().top+50,60,20);
add(lblroomname);
txtroomname=new TextField();
txtroomname.reshape(insets().left+75,insets().top+50,60,20);
add(txtroomname);
okBtn=new Button("Login");
okBtn.reshape(insets().left+25,insets().top+80,60,20);
add(okBtn);
// okBtn.addActionListener(this);
exitBut=new Button("EXIT");
exitBut.reshape(insets().left+50,insets().top+80,60,20);
add(exitBut);
// exitBut.addActionListener(this);
public static void main(String[] args)
// Create a JFrame
JFrame frame = new JFrame("client side");
// Create a outer class object
outer outerobj = new outer();
// Add the outer to the JFrame
frame.getContentPane().add(outerobj, BorderLayout.WEST);
// Set Jframe size
frame.setSize(800, 400);
//set resizable true
frame.setResizable(true);
// Set JFrame to visible
frame.setVisible(true);
// set the close operation so that the Application terminates when closed
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
when i compile it it compiles but gives run time error like this
RUN TIME error:
Exception in thread "main" java.lang.IllegalArgumentException: adding a window
to a container
at java.awt.Container.addImpl(Container.java:434)
at java.awt.Container.add(Container.java:345)
at outer.main(outer.java:75)
Press any key to continue...
i know erroe in this line
frame.getContentPane().add(outerobj, BorderLayout.WEST);
but how shall i add to get the proper layout by getting benifit of insets method
reply soon
pleaseYou can't add a frame to a frame.
Try chaing the class definition from
public class outer extends Frameto
public class outer extends PanelPlease note to format your code (you'll get a faster response) use [ code]
Object names should always start with a capital letter. outer --> Outer -
AWT to SWING conversion - i am so lost!!!
Hi,
i am hoping somebody's expertise can help me. i am still relatively new to java and have created this class in java which has an AWT gui, that enables a user to click a "load" button, which the user can then select the jpeg they want to load and the class loads the picture in the canvas. Once i had created it i realised that i actually need to do it in SWING, but the problem is that i dont know how to convert this AWT class to a SWING based class. I have included the code below, and would really appreciate it if somebody can show me how to convert my code so that it is in SWING instead.
Thank you for your help.
kind regards,
Very Confused One
--------------------------START OF CODE [ImageDicer.java] --------------------------
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.util.*;
public class ImageDicer extends Frame
public static void main(String[] args)
String fileName = "default";
if (args.length > 0) fileName = args[0];
new ImageDicer(fileName);
private static final String kBanner = "ImageDicer v1.0";
public ImageDicer(String fileName)
super(kBanner);
createUI();
loadImage(fileName);
setVisible(true);
private Panel mControlPanel;
private void createUI()
setFont(new Font("Serif", Font.PLAIN, 12));
setLayout(new BorderLayout());
final Label statusLabel = new Label("Welcome to " + kBanner + ".");
Button loadButton = new Button("Load...");
loadButton.addActionListener(new ActionListener()
public void actionPerformed(ActionEvent ae)
FileDialog fd = new FileDialog(ImageDicer.this);
fd.show();
if (fd.getFile() == null) return;
String path = fd.getDirectory() + fd.getFile();
loadImage(path);
mControlPanel = new Panel();
mControlPanel.add(loadButton);
mControlPanel.add(statusLabel);
add(mControlPanel, BorderLayout.SOUTH);
addWindowListener(new WindowAdapter()
public void windowClosing(WindowEvent e)
dispose();
System.exit(0);
private void adjustToImageSize()
if (!isDisplayable()) addNotify(); // Do this to get valid Insets.
Insets insets = getInsets();
int w = mBufferedImage.getWidth() + insets.left + insets.right;
int h = mBufferedImage.getHeight() + insets.top + insets.bottom;
h += mControlPanel.getPreferredSize().height;
setSize(w, h);
private void center()
Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
Dimension d = getSize();
int x = (screen.width - d.width) / 2;
int y = (screen.height - d.height) / 2;
setLocation(x, y);
private BufferedImage mBufferedImage;
private void loadImage(String fileName)
Image image = Toolkit.getDefaultToolkit().getImage(fileName);
MediaTracker mt = new MediaTracker(this);
mt.addImage(image, 0);
try { mt.waitForID(0); }
catch (InterruptedException ie) { return; }
if (mt.isErrorID(0)) return;
mBufferedImage = new BufferedImage(image.getWidth(null),
image.getHeight(null),
BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = mBufferedImage.createGraphics();
g2.drawImage(image, null, null);
adjustToImageSize();
center();
validate();
repaint();
setTitle(kBanner + ": " + fileName);
public void paint(Graphics g)
if (mBufferedImage == null) return;
Insets insets = getInsets();
g.drawImage(mBufferedImage, insets.left, insets.top, null);
--------------------------END OF CODE [ImageDicer.java] --------------------------Thanks again for your assistance. The class manages to compile now but there seems to be a bug in the program. Everytime i run the class, the window loads, but the load button does not appear. It only appears when you click aimlessly at the bottom of the window until u luckily click on it. i cannot understand why this is happening :s
Again i am greatful for your help.
import javax.swing.*;
import javax.swing.border.*;
import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import java.util.*;
import javax.imageio.ImageIO;
import java.net.*;
import javax.swing.filechooser.*;
public class ImageDicer extends JFrame
String kBanner = "ImageDicer v1.0";
JPanel mControlPanel;
JLabel statusLabel;
JButton loadButton;
public BufferedImage mBufferedImage;
public ImageDicer(String fileName)
{ Container pane=getContentPane();
setTitle(kBanner);
pane.setLayout(new BorderLayout());
statusLabel = new JLabel("Welcome to " + kBanner + ".");
loadButton = new JButton("Load...");
loadButton.addActionListener(new ActionListener()
public void actionPerformed(ActionEvent ae)
{ JFileChooser fd = new JFileChooser();
int returnVal=fd.showOpenDialog(ImageDicer.this);
if(returnVal==JFileChooser.APPROVE_OPTION)
{if (fd.getSelectedFile() == null)
{return;}
File file=fd.getSelectedFile();
String path=(String)file.getPath();
loadImage(path);
mControlPanel = new JPanel();
mControlPanel.add(loadButton);
mControlPanel.add(statusLabel);
pane.add( BorderLayout.SOUTH, mControlPanel);
public void adjustToImageSize()
if (!isDisplayable()) addNotify(); // Do this to get valid Insets.
Insets insets = getInsets();
int w = mBufferedImage.getWidth() + insets.left + insets.right;
int h = mBufferedImage.getHeight() + insets.top + insets.bottom;
h += mControlPanel.getPreferredSize().height;
setSize(w, h);
public void center()
Dimension screen = Toolkit.getDefaultToolkit().getScreenSize();
Dimension d = getSize();
int x = (screen.width - d.width) / 2;
int y = (screen.height - d.height) / 2;
setLocation(x, y);
public void loadImage(String fileName)
Image image = Toolkit.getDefaultToolkit().getImage(fileName);
MediaTracker mt = new MediaTracker(this);
mt.addImage(image, 0);
try { mt.waitForID(0); }
catch (InterruptedException ie) { return; }
if (mt.isErrorID(0)) return;
mBufferedImage = new BufferedImage(image.getWidth(null),
image.getHeight(null),
BufferedImage.TYPE_INT_RGB);
Graphics2D g2 = mBufferedImage.createGraphics();
g2.drawImage(image, null, null);
adjustToImageSize();
center();
validate();
repaint();
setTitle(kBanner + ": " + fileName);
public void paint(Graphics g)
if (mBufferedImage == null) return;
Insets insets = getInsets();
g.drawImage(mBufferedImage, insets.left, insets.top, null);
public static void main(String[] args)
String fileName = "default";
if (args.length > 0) fileName = args[0];
ImageDicer img=new ImageDicer(fileName);
img.setSize(800,600);
img.show();
} -
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. -
Differences between awt and swing
Ive written the following code, however Ive implemented the gui in awt rather then swing. Ive been told it hs too be in swing. What is the difference between swing and awt what will I need to change in my program so that its done using swing rather then the awt? Heres the code:
// pp.java
// Grant Brown
// 22/02/02
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
// =========================================================
// Class: pp
// This class drives the customer manager. It contains the
// main method which gets called as soon as this application
// begins to run.
// =========================================================
class pp extends Frame implements ActionListener
// Container of customer objects
private Vector customers = new Vector (100);
// List of names component. (Must specify java.awt in
// front of List to distinguish the List class in the
// java.awt package from the List class in the java.util
// package.)
private java.awt.List names = new java.awt.List ();
// Delete and update button components.
private Button delete;
private Button update;
// Default constructor.
public pp ()
// Assign "Paper Round Manager" to title bar of frame window.
super ("Paper Round Manager");
// Add a listener that responds to window closing
// events. When this event occurs (by clicking on the
// close box in the title bar), save customers and exit.
addWindowListener (new WindowAdapter ()
public void windowClosing
(WindowEvent e)
saveCustomers ();
System.exit (0);
// Place an empty label in the north part of the frame
// window. This is done to correct an AWT positioning
// problem.
Label l = new Label ();
add ("North", l);
// Place the names component in the center part of the
// frame window.
add ("Center", names);
// Create a panel object to hold four buttons.
Panel p = new Panel ();
Button b;
// Add an Insert button to the Panel object and register
// the current pp object as a listener for button events.
p.add (b = new Button ("Insert"));
b.addActionListener (this);
// Add a Delete button to the Panel object and register
// the current pp object as a listener for button events.
p.add (delete = new Button ("Delete"));
delete.addActionListener (this);
// The Delete button should be disabled until there is at
// least one customer to delete.
delete.setEnabled (false);
// Add an Update button to the Panel object and register
// the current pp object as a listener for button events.
p.add (update = new Button ("Update"));
update.addActionListener (this);
// The Update button should be disabled until there is at
// least one customer to update.
update.setEnabled (false);
// Add a Finish button to the Panel object and register
// the current customer object as a listener for button events.
p.add (b = new Button ("Finish"));
b.addActionListener (this);
// Add the panel object to the frame window container.
add ("South", p);
// Set the background of the frame window container to
// lightGray
setBackground (Color.lightGray);
// Set the size of the frame window container to 400
// pixels horizontally by 200 pixels vertically.
setSize (400, 200);
// Allow the user to resize the frame window.
setResizable (true);
// Load all contacts.
loadCustomers ();
// Make sure that the frame window is visible.
setVisible (true);
public void actionPerformed (ActionEvent e)
if (e.getActionCommand ().equals ("Delete"))
delete ();
else
if (e.getActionCommand ().equals ("Finish"))
saveCustomers ();
System.exit (0);
else
if (e.getActionCommand ().equals ("Insert"))
insert ();
else
update ();
public Insets getInsets ()
// Return an Insets object that describes the number of
// pixels to reserve as a border around the edges of the
// frame window.
return new Insets (10, 10, 10, 10);
public static void main (String [] args)
// Create a new pp object and let it do its thing.
new pp ();
private void delete ()
// Obtain index of selected contact item from the names
// component.
int index = names.getSelectedIndex ();
// If no item was selected, index is -1. We cannot update
// a contact if no contact item in the names component was
// selected - because we would have nothing to work with.
if (index != -1)
// Remove the contact item from the names component.
names.remove (index);
// Remove the Customer object from the contacts Vector
// object.
customers.remove (index);
// If there are no more customers ...
if (customers.size () == 0)
delete.setEnabled (false);
update.setEnabled (false);
else
// Make sure that the first contact item in the names
// list is highlighted.
names.select (0);
private void insert ()
// Create an Insert data entry form to enter information
// for a new customer.
DataEntryForm def = new DataEntryForm (this, "Insert");
// If the bOk Boolean flag is set, this indicates the user
// exited the form by pressing the Ok button.
if (def.bOk)
// Create a Contact object and assign information from
// the form to its fields.
Customer temp = new Customer ();
temp.name = new String (def.name.getText ());
temp.publication = new String (def.publication.getText ());
temp.round = new String (def.round.getText ());
temp.address = new String (def.address.getText ());
temp.phone = new String (def.phone.getText ());
// Add a new customer item to the names component.
names.add (temp.name + ", " + temp.publication);
// Add the Customer object to the contacts Vector
// object.
customers.add (temp);
// Make sure that the Delete and Update buttons are
// enabled.
delete.setEnabled (true);
update.setEnabled (true);
// Destroy the dialouge box.
def.dispose ();
// Make sure that the first customer item in the names list
// is highlighted.
names.select (0);
// ===========================================================
// Load all contacts from contacts.dat into the contacts
// Vector object. Also, make sure that the last name/first
// name from each contact is combined into a String object and
// inserted into the names component - as a contact item.
// ===========================================================
private void loadCustomers ()
FileInputStream fis = null;
try
fis = new FileInputStream ("Customers.dat");
DataInputStream dis = new DataInputStream (fis);
int nCustomers = dis.readInt ();
for (int i = 0; i < nCustomers; i++)
Customer temp = new Customer ();
temp.name = dis.readUTF ();
temp.publication = dis.readUTF ();
temp.round = dis.readUTF ();
temp.address = dis.readUTF ();
temp.phone = dis.readUTF ();
names.add (temp.name + ", " + temp.publication);
customers.add (temp);
if (nCustomers > 0)
delete.setEnabled (true);
update.setEnabled (true);
catch (IOException e)
finally
if (fis != null)
try
fis.close ();
catch (IOException e) {}
// Make sure that the first contact item in the names list
// is highlighted.
names.select (0);
// ========================================================
// Save all Customer objects from the customer Vector object
// to customer.dat. The number of customerss are saved as an
// int to make it easy for loadCustomers () to do its job.
// ========================================================
private void saveCustomers ()
FileOutputStream fos = null;
try
fos = new FileOutputStream ("customers.dat");
DataOutputStream dos = new DataOutputStream (fos);
dos.writeInt (customers.size ());
for (int i = 0; i < customers.size (); i++)
Customer temp = (Customer) customers.elementAt (i);
dos.writeUTF (temp.name);
dos.writeUTF (temp.publication);
dos.writeUTF (temp.round);
dos.writeUTF (temp.address);
dos.writeUTF (temp.phone);
catch (IOException e)
MsgBox mb = new MsgBox (this, "PP Error",
e.toString ());
mb.dispose ();
finally
if (fos != null)
try
fos.close ();
catch (IOException e) {}
private void update ()
// Obtain index of selected customer item from the names
// component.
int index = names.getSelectedIndex ();
// If no item was selected, index is -1. We cannot update
// a customer if no customer item in the names component was
// selected - because we would have nothing to work with.
if (index != -1)
// Obtain a reference to the customer object (from the
// customers Vector object) that is associated with the
// index.
Customer temp = (Customer) customers.elementAt (index);
// Create and display an update entry form.
DataEntryForm def = new DataEntryForm (this, "Update",
temp.name,
temp.publication,
temp.round,
temp.address,
temp.phone);
// If the user pressed Ok...
if (def.bOk)
// Update the customer information in the customers
// Vector object.
temp.name = new String (def.name.getText ());
temp.publication = new String (def.publication.getText ());
temp.round = new String (def.round.getText ());
temp.address = new String (def.address.getText ());
temp.phone = new String (def.phone.getText ());
// Make sure the screen reflects the update.
names.replaceItem (temp.name + ", " + temp.publication,
index);
// Destroy the dialouge box.
def.dispose ();
// Make sure that the first customer item in the names
// list is highlighted.
names.select (0);Ive doen pretty much what you said burt now my program isnt working at all. The window comes up but instead of doing something when you click the button it just throws shit loads of exceptions. Heres my abridged code
// pp.java
// Grant Brown
// 22/02/02
import java.awt.*;
import java.awt.event.*;
import java.io.*;
import java.util.*;
import javax.swing.*;
// =========================================================
// Class:PP
// This class drives the Paper Round manager. It contains the
// main method which gets called as soon as this application
// begins to run.
// =========================================================
class pp extends JFrame implements ActionListener
// Container of customer objects (one object per customer)
private Vector customers = new Vector (100);
// List of names component. (Must specify java.awt in
// front of List to distinguish the List class in the
// java.awt package from the List class in the java.util
// package.)
private java.awt.List names = new java.awt.List ();
// Delete and update button components.
private JButton delete;
private JButton update;
// Default constructor.
public pp ()
// Assign Contact Manager to title bar of frame window.
super ("Paper Round Manager");
// Add a listener that responds to window closing
// events. When this event occurs (by clicking on the
// close box in the title bar), save contacts and exit.
addWindowListener (new WindowAdapter ()
public void windowClosing
(WindowEvent e)
saveCustomers ();
System.exit (0);
// Place an empty label in the north part of the frame
// window. This is done to correct an AWT positioning
// problem. (One thing that you'll come to realize as
// you work with the AWT is that there are lots of bugs.)
JLabel l = new JLabel ();
getContentPane().add ("North", l);
// Place the names component in the center part of the
// frame window.
getContentPane().add ("Center", names);
// Create a panel object to hold four buttons.
JPanel p = new JPanel ();
JButton b;
// Add an Insert button to the Panel object and register
// the current cm object as a listener for button events.
p.add (b = new JButton ("Insert"));
b.addActionListener (this);
// Add a Delete button to the Panel object and register
// the current cm object as a listener for button events.
p.add (delete = new JButton ("Delete"));
delete.addActionListener (this);
// The Delete button should be disabled until there is at
// least one contact to delete.
delete.setEnabled (false);
// Add an Update button to the Panel object and register
// the current cm object as a listener for button events.
p.add (update = new JButton ("Update"));
update.addActionListener (this);
// The Update button should be disabled until there is at
// least one contact to update.
update.setEnabled (false);
// Add a Finish button to the Panel object and register
// the current cm object as a listener for button events.
p.add (b = new JButton ("Finish"));
b.addActionListener (this);
// Add the panel object to the frame window container.
getContentPane().add ("South", p);
// Set the background of the frame window container to
// lightGray (to give a pleasing effect).
setBackground (Color.lightGray);
// Set the size of the frame window container to 400
// pixels horizontally by 200 pixels vertically.
setBounds (50, 100, 400, 200);
// Do not allow the user to resize the frame window.
loadCustomers ();
// Load all contacts.
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
// Make sure that the frame window is visible.
setVisible (true);
public void actionPerformed (ActionEvent e)
if (e.getActionCommand ().equals ("Delete"))
delete ();
else
if (e.getActionCommand ().equals ("Finish"))
saveCustomers ();
System.exit (0);
else
if (e.getActionCommand ().equals ("Insert"))
insert ();
else
update ();
public Insets getInsets ()
// Return an Insets object that describes the number of
// pixels to reserve as a border around the edges of the
// frame window.
return new Insets (10, 10, 10, 10);
public static void main (String [] args)
// Create a new cm object and let it do its thing.
new pp ();
private void delete ()
// Obtain index of selected customer item from the names
// component.
int index = names.getSelectedIndex ();
// If no item was selected, index is -1. We cannot update
// a contact if no contact item in the names component was
// selected - because we would have nothing to work with.
if (index != -1)
// Remove the customer item from the names component.
names.remove (index);
// Remove the Customer object from the contacts Vector
// object.
customers.remove (index);
// If there are no more customers ...
if (customers.size () == 0)
delete.setEnabled (false);
update.setEnabled (false);
else
// Make sure that the first contact item in the names
// list is highlighted.
names.select (0);
private void insert ()
// Create an Insert data entry form to enter information
// for a new contact.
DataEntryForm def = new DataEntryForm (this, "Insert");
// If the bOk Boolean flag is set, this indicates the user
// exited the form by pressing the Ok button.
if (def.bOk)
// Create a Customer object and assign information from
// the form to its fields.
Customer temp = new Customer ();
temp.name = new String (def.name.getText ());
temp.publication = new String (def.publication.getText ());
temp.address = new String (def.address.getText ());
temp.round = new String (def.round.getText ());
temp.phone = new String
(def.phone.getText ());
// Add a new customer item to the names component.
names.add (temp.publication + ", " + temp.address);
// Add the Customer object to the contacts Vector
// object.
customers.add (temp);
// Make sure that the Delete and Update buttons are
// enabled.
delete.setEnabled (true);
update.setEnabled (true);
// Destroy the dialog box.
def.dispose ();
// Make sure that the first customer item in the names list
// is highlighted.
names.select (0);
// ===========================================================
// Load all customers from customers.dat into the customers
// Vector object. Also, make sure that the last name/first
// name from each contact is combined into a String object and
// inserted into the names component - as a contact item.
// ===========================================================
private void loadCustomers ()
FileInputStream fis = null;
try
fis = new FileInputStream ("customers.dat");
DataInputStream dis = new DataInputStream (fis);
int nCustomers = dis.readInt ();
for (int i = 0; i < nCustomers; i++)
Customer temp = new Customer ();
temp.name = dis.readUTF ();
temp.publication = dis.readUTF ();
temp.address = dis.readUTF ();
temp.round = dis.readUTF ();
temp.phone = dis.readUTF ();
names.add (temp.publication + ", " + temp.address);
customers.add (temp);
if (nCustomers > 0)
delete.setEnabled (true);
update.setEnabled (true);
catch (IOException e)
finally
if (fis != null)
try
fis.close ();
catch (IOException e) {}
// Make sure that the first customer item in the names list
// is highlighted.
names.select (0);
// ========================================================
// Save all customer objects from the contacts Vector object
// to customers.dat. The number of contacts are saved as an
// int to make it easy for loadCustomers () to do its job.
// ========================================================
private void saveCustomers ()
FileOutputStream fos = null;
try
fos = new FileOutputStream ("customers.dat");
DataOutputStream dos = new DataOutputStream (fos);
dos.writeInt (customers.size ());
for (int i = 0; i < customers.size (); i++)
Customer temp = (Customer) customers.elementAt (i);
dos.writeUTF (temp.name);
dos.writeUTF (temp.publication);
dos.writeUTF (temp.address);
dos.writeUTF (temp.round);
dos.writeUTF (temp.phone);
catch (IOException e)
MsgBox mb = new MsgBox (this, "PP Error",
e.toString ());
mb.dispose ();
finally
if (fos != null)
try
fos.close ();
catch (IOException e) {}
private void update ()
// Obtain index of selected customer item from the names
// component.
int index = names.getSelectedIndex ();
// If no item was selected, index is -1. We cannot update
// a customer if no customer item in the names component was
// selected - because we would have nothing to work with.
if (index != -1)
// Obtain a reference to the Customer object (from the
// customer Vector object) that is associated with the
// index.
Customer temp = (Customer) customers.elementAt (index);
// Create and display an update entry form.
DataEntryForm def = new DataEntryForm (this, "Update",
temp.name,
temp.publication,
temp.address,
temp.round,
temp.phone);
// If the user pressed Ok...
if (def.bOk)
// Update the customer information in the customers
// Vector object.
temp.name = new String (def.name.getText ());
temp.publication = new String (def.publication.getText ());
temp.address = new String (def.address.getText ());
temp.round = new String (def.round.getText ());
temp.phone = new String (def.phone.getText ());
// Make sure the screen reflects the update.
names.replaceItem (temp.publication + ", " + temp.address,
index);
// Destroy the dialog box.
def.dispose ();
// Make sure that the first customer item in the names
// list is highlighted.
names.select (0);
// ========================================================
// Class: Customer
// This class describes the contents of a business customer.
// ========================================================
class Customer
public String name;
public String publication;
public String address;
public String round;
public String phone;
// ==========================================================
// Class: DataEntryForm
// This class provides a data entry form for entering customer
// information.
// ==========================================================
class DataEntryForm extends JDialog implements ActionListener
// bOk is a boolean flag. When true, it indicates that
// the Ok button was pressed to terminate the dialog box
// (as opposed to the Cancel button).
public boolean bOk;
// The following components hold the text that the user
// entered into the visible text fields.
public JTextField name;
public JTextField publication;
public JTextField address;
public JTextField round;
public JTextField phone;
public void actionPerformed (ActionEvent e)
// If the user pressed the Ok button, indicate this
// by assigning true to bOk.
if (e.getActionCommand ().equals ("Ok"))
bOk = true;
// Destroy the dialog box and return to the point
// just after the creation of the DataEntryForm object.
dispose ();
public DataEntryForm (JFrame parent, String title)
// Call the other constructor. The current constructor
// is used for insert operations. The other constructor
// is used for update operations.
this (parent, title, "", "", "", "", "");
public DataEntryForm (JFrame parent, String title,
String name, String publication,
String address, String round,
String phone)
// Initialize the superclass layer.
super (parent, title, true);
// Choose a grid bag layout so that components can be more
// accurately positioned. (It looks nicer.)
setLayout (new GridBagLayout ());
// Add appropriate first name, last name, phone, fax, and
// email components to the current DataEntryForm container.
// (Remember, DataEntryForm is a subclass of Dialog.
// Dialog is a container. Therefore, DataEntryForm
// inherits the ability to be a container.)
addComponent (this, new JLabel ("Name: "), 0, 0, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.name = new JTextField (15);
addComponent (this, this.name, 1, 0, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.name.setText (name);
addComponent (this, new JLabel ("Publications: "), 0, 1, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.publication = new JTextField (15);
addComponent (this, this.publication, 1, 1, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.publication.setText (publication);
addComponent (this, new JLabel ("Address "), 0, 2, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.address = new JTextField (15);
addComponent (this, this.address, 1, 2, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.address.setText (address);
addComponent (this, new JLabel ("Round No "), 0, 3, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.round = new JTextField (15);
addComponent (this, this.round, 1, 3, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.round.setText (round);
addComponent (this, new JLabel ("Phone Number "), 0, 4, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.WEST);
this.phone = new JTextField (15);
addComponent (this, this.phone, 1, 4, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
if (title.equals ("Update"))
this.phone.setText (phone);
addComponent (this, new JLabel (""), 0, 5, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
addComponent (this, new JLabel (""), 1, 5, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
JButton b;
// Add an Ok button to this container.
addComponent (this, b = new JButton ("Ok"), 0, 6, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
b.addActionListener (this);
// Add a Cancel button to this container.
addComponent (this, b = new JButton ("Cancel"), 1, 6, 1, 1,
GridBagConstraints.NONE,
GridBagConstraints.CENTER);
b.addActionListener (this);
// Set the size of the dialog window to 250 pixels
// horizontally by 200 pixels vertically.
setSize (250, 200);
// Do not allow users to resize the dialog window.
setResizable (false);
// Make sure that the dialog window is visible.
setVisible (true);
private void addComponent (Container con, Component com,
int gridx, int gridy,
int gridw, int gridh, int fill,
int anchor)
// Get the current layout manager. It is assumed to
// be a GridBagLayout object.
LayoutManager lm = con.getLayout ();
// Create a GridBagConstraints object to make it
// possible to customize component positioning.
GridBagConstraints gbc = new GridBagConstraints ();
// Assign the x and y grid positions.
gbc.gridx = gridx;
gbc.gridy = gridy;
// Assign the number of grid blocks horizontally and
// vertically that are occupied by the component.
gbc.gridwidth = gridw;
gbc.gridheight = gridh;
// Specify the component's resize policy (fill) and
// the direction in which the component is positioned
// when its size is smaller than available space (anchor).
gbc.fill = fill;
gbc.anchor = anchor;
// Set the new constraints that the grid bag layout
// manager will use.
((GridBagLayout) lm).setConstraints (com, gbc);
// Add the component to the container.
con.add (com);
// ===========================================================
// Class: MsgBox
// This class displays a message box to the user. The message
// is usually an error message. The user must press the Ok
// button to terminate the message box.
// ===========================================================
class MsgBox extends JDialog implements ActionListener
public void actionPerformed (ActionEvent e)
// Terminate the dialog box in response to the user
// pressing the Ok button.
dispose ();
public MsgBox (JFrame parent, String title, String msg)
// Initialize the superclass layer.
super (parent, title, true);
// Store the msg argument in a Label object and add
// this object to the center part of the dialog window.
JLabel l = new JLabel (msg);
add ("Center", l);
// Create a Button object and add it to the south part
// of the dialog window.
JButton b = new JButton ("Ok");
add ("South", b);
// Make the current object a listener to events that
// occur as a result of the user pressing the Ok
// button.
b.addActionListener (this);
// Make sure that the Ok button has the focus.
b.requestFocus ();
// Do not allow users to resize the dialog window.
setResizable (false);
// Allow the layout manager to choose an appropriate
// size for the dialog window.
pack ();
// Make sure that the dialog window is visible.
setVisible (true);
} -
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(). -
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 -
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 ?
THXHi !
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. -
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 -
I had an argument with my friend on Swing and it's platform independence. My friends argument was that, swing cannot be platform independent if one of it's parent classes has a native method.
For eg: JLabel extends JComponent extends Container extends Component
And Component has a native method, and hence swing can't be purely Java? Even I am confused? Can someone explain?Hi,
as far as I understood it (but I might be wrong) the difference between AWT and Swing is the following (among others):
With AWT there are native calls to draw the components, eg. the OS says how to draw a button. These are known as heavyweight components.
With Swing all components are drawn with Java (except some Windows). These are known as lightweight components. (This also allows the concept of the pluggable L&F.)
Yes, Swing components do extend AWT components, but I think that some methods are overriden or there are some switches or something like this, to avoid those native calls.
-Puce -
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
bhaskarhi,
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........... -
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
Maybe you are looking for
-
How do I connect to my Airports/time capsules over the internet using the mobileme function under icloud?
-
Miro-want to debit a material without using a purchase order reference
Hi, I have activated direct posting to material account but when make MIRO, the system generates the accounting document on GL account not material account and dont update the material stock. Where to configure to make posting on material account. Re
-
In Windows XP, wireless Keyboard freezes, then repeats key over and over
When I'm working in Windows XP, my wireless apple aluminum keyboard will freeze for a brief second, then it will continue to repeat the last key I typed for while. I've searched through all the forums and cannot find a solution to this problem. Any i
-
Identifying triger point & stoping an idoc from getting generated in SD
We have 2 boxes KLE 420 ( CRM box) & KLE 430 ( SC box) As per original business flow 1) Sales order is generated in 420 ( order type Z001, item category ZAN1 ) 2) idoc is generated and message/details is transferred to 430 ( Z002, ZAN2 ) 3) in 430 th
-
Is the a clear cut best practice procedure for conducting data migration from one company to a new one ?