Java.awt.Toolkit.getScreenSize()

Hello again world.
I'm a little confused here. I have these two lines in a program:
Toolkit tKit = Toolkit.getDefaultToolkit();
Dimension size = tKit.getScreenSize();
Reading the API, I notice that "getScreenSize()" is declared abstract.
I was under the impression that abstract methods need to be overridden and have no actual code.
if (that's correct)
return "What's up with that second line?";
else
return "What's the deal with abstract methods?";Thank you one and all.
Ciao for now.

I don't understand.
How does that tell me the "getScreenSize()" is
defined?
Do I just trust that the abstract method has been
overridden in that implementation?Abstract methods can only exist in abstract classes and interfaces. A non-abstract class, commonly referred to as a concrete classes, cannot have abstract methods. Only concrete classes can be instanciated, therefore, if you have an instance of some abstract class, then you know that it is an instance of some concrete subclass of the abstract class. This tells you that all abstract methods have been implemented. So, just the simple fact that you actually have an instance of the object tell you that all the abstract methods are implemented.
Where are these classes anyhow?Doesn't matter. Like someone said earlier, that is the beauty of polymorphism and inheritance.

Similar Messages

Deprecation warning for getFontMetrics(java.awt.Font) in java.awt.Toolkit

Hi all,
When I use the following code
JComponent c;
FontMetrics metrics = getToolkit().getFontMetrics(c.getFont());
I get this following warning during compilation:-
warning: getFontMetrics(java.awt.Font) in java.awt.Toolkit has been deprecated
JDK suggests to use getLineMetrics() of the Font class.
But there's an issue with that: if I use getLineMetrics(), there is no API method that I can use to get the width of a string as opposed to FontMetrics which provides stringWidth(String str) method for that purpose. In fact all the methods in FontMetrics are not mapped into LineMetrics.
Could anyone please help or provide me at least some pointers on how to tackle this issue so that I can get rid of the deprecated method along with the existing methods mapped to equivalent APIs? The bottomline is that I should be able to maintain the existing functinality of my application for those part of code that uses getToolkit().getFontMetrics().
Thank you for your help in advance.
-Sanjoy Das

Use Graphics.getFontMetrics(font) instead.
After creation your frame and calling frame.show();
You can access it like that
frame.show();
frame.getGraphics().getFontMetrics(new Font("Arial",0,10));
before showing graphics is null.
Or just create a BufferedImage and ask it for graphics.
BufferedImage img=new BufferedImage(...);
img.getGraphics().getFontMetrics(font);
regards
Stas

Quality of Cursors created with java.awt.Toolkit(createCutsomCursor)

Hi -
I encountered a small problem while creating my own cursors for my Java application , I used the java.awt.Toolkit Objects createCustomCursor method to use a .GIF image as a cursor ... it worked but the quality of that cursor is horrible, the outline is rough ... I tried the same with a transparent PNG file afterwards unfortunately the same result , does anyone know why the quality is that bad or may this just be a problem of the choosen color pool ?
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-- Harald Scheckenbacher

I noticed this problem too. It looks like the routine is generating cursors which are scaled to to the maximum size of the system. On my win XP system,
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int maxColors = toolkit.getMaximumCursorColors();
return 32,32 and 256 respectively
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Java.awt.Toolkit - Coldfusion - HELP

Greetings.
I am having a hard time with the following code:
<cfobject action="create" type="java" class="java.awt.Toolkit" name="fileObj">
<cfscript>
img = fileObj.getDefaultToolkit().getImage("images/products/39321.jpg");
width = img.getwidth();
height = img.getheight();
</cfscript>
<cfoutput>#height#</cfoutput>
I keep getting the following error:
java.lang.NoClassDefFoundError
My version of Java is 1.4.2. I'm running Redhat Linux 4.0. Coldfusion MX 6.1.
I know this isn't a Coldfusion forum, but I really need some help here.
I'm new to Java technologies, so any help will be greatly appreciated.

can ColdFusion load Java objects?
Presuming that it can, then ColdFusion probably needs some configuration to tell it the Java directory or where the class files are (JavaHome/jre/lib/rt.jar)

Substitute of java.awt.ToolKit.getDefaultToolKit.beep()

Hello everybody. I am designing a Swing Application and there I am using java.awt.ToolKit.getDefaultToolKit.beep() method to generate sound in various operations. I want to know is it possible to generate own sound as a substitute of this method? I think it is possible. How can I do this? Thank you.

Thank you for giving reply.
As I wish to play .mp3 file I had downloaded an API from Javalobby . I tried it, here is my code :
package player;
import java.io.File;
import java.io.IOException;
import javax.sound.sampled.AudioFormat;
import javax.sound.sampled.AudioInputStream;
import javax.sound.sampled.AudioSystem;
import javax.sound.sampled.DataLine;
import javax.sound.sampled.SourceDataLine;
* @author Tanmoy
* @Super Scientific Calculator
* @version 1.2010
public class Player {
     private File audioFile;
     public Player(String path) {
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     public void play() {
          AudioInputStream din = null;
          try {
               AudioInputStream in = AudioSystem.getAudioInputStream(audioFile);
               AudioFormat baseFormat = in.getFormat();
               AudioFormat decodedFormat = new AudioFormat(
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                    baseFormat.getSampleRate(), 16, baseFormat.getChannels(),
                    baseFormat.getChannels() * 2, baseFormat.getSampleRate(),
                    false);
               din = AudioSystem.getAudioInputStream(decodedFormat, in);
               DataLine.Info info = new DataLine.Info(SourceDataLine.class, decodedFormat);
               SourceDataLine line = (SourceDataLine) AudioSystem.getLine(info);
               if (line != null) {
                    line.open(decodedFormat);
                    byte[] data = new byte[4096];
                    line.start();
                    int nBytesRead;
                    while ((nBytesRead = din.read(data, 0, data.length)) != -1) {
                         line.write(data, 0, nBytesRead);
                    line.drain();
                    line.stop();
                    line.close();
                    din.close();
          } catch (Exception e) {
          } finally {
               if (din != null) {
                    try {
                         din.close();
                    } catch (IOException e) {
}And the calling, piece of code is :
try {
                              Parser parser = new Parser(parsingString, displayPanel.getCurrentBase(),
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                              String output = parser.solve();
                              displayPanel.outputTextField.setText(output);
                              displayPanel.outputTextField.setCaretPosition(displayPanel.outputTextField.getText().length());
                              displayPanel.charLabel.setText((Integer.toString(output.length())));
                              if (message == null) {
                                   message = "No Exception";
                         } catch (InvalidSyntaxException invalidSyntaxException) {
                              message = invalidSyntaxException.getMessage();
                              JOptionPane.showMessageDialog(null, message, "Error", JOptionPane.ERROR_MESSAGE);
                              new Player("/resources/what_the_hell.mp3").play();
                              displayPanel.outputTextField.setText("0");
                              displayPanel.charLabel.setText("0");
                         }But I can not able to here the sound.
What to do now?
Thank you.

Java.awt.Dialog in Java 1.6 has a memory leak

When a modal Dialog opens a modal sub-dialog, the Dialog stays in memory after both the sub-dialog and the Dialog itself is disposed.
The field that contains the leaked object is Dialog.modalDialogs (static). The methods which causes the leak are Dialog.modalHide and Dialog.modalShow.
Whenever a modal Dialog is opened, Dialog.modalShow is called, and adds itself to Dialog.modalDialogs.
When it closes, Dialog.modalHide is called and removes one copy of itself from Dialog.modalDialogs. Then Dialog.modalShow is called on all previously blocked modal dialogs. When the sub-dialog is opened and closed, Dialog.modalDialogs contains two references to the main Dialog, and only one of them is removed when Dialog.modalHide for that Dialog is called.
To detect the leak, just put a break point in Dialog.modalHide, after modalDialogs.remove(this);. When opening a Dialog and closing it without opening a sub-dialog, the Dialog.modalDialogs field should be empty. When a sub-dialog was opened and closed before the main Dialog is closed, the Dialog.modalDialogs field contains a reference to the disposed main Dialog.
This leak does not exist in 1.5.0_10 (no Dialog.modalDialogs field). I have searched the bug database, but I have not found this bug there. Could anyone confirm this?
A simple code to reproduce the leak:
import java.awt.Dimension;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowEvent;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
public class Test {
   public static void main(String[] args) {
      final JFrame frame = new JFrame() {
         protected void processWindowEvent(WindowEvent e) {
            super.processWindowEvent(e);
            if (e.getID() == WindowEvent.WINDOW_CLOSING) {
               System.exit(0);
      JButton button = new JButton("Dialog");
      button.addActionListener(new ActionListener() {
         public void actionPerformed(ActionEvent aE) {
            JButton subButton = new JButton("SubDialog");
            subButton.addActionListener(new ActionListener() {
               public void actionPerformed(ActionEvent aE) {
                  JOptionPane.showMessageDialog(frame, "SubDialog");
            JOptionPane.showMessageDialog(frame, subButton);
      frame.getContentPane().add(button);
      frame.pack();
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      Dimension screenSize = Toolkit.getDefaultToolkit().getScreenSize();
      Dimension frameSize = frame.getSize();
      if (frameSize.height > screenSize.height) {
         frameSize.height = screenSize.height;
      if (frameSize.width > screenSize.width) {
         frameSize.width = screenSize.width;
      frame.setLocation((screenSize.width - frameSize.width) / 2,
            (screenSize.height - frameSize.height) / 2);
      frame.setVisible(true);
}

Sorry, I just found the bug in the bugdatabase (with google of course,):
[http://bugs.sun.com/bugdatabase/view_bug.do?bug_id=6497929]

Eexception in java.awt.AWTError

Hi all,
I am starting with java in my Ubuntu box, and am faced with a problem.
Consider a simple program
import javax.swing.*;
import java.awt.*;
class helloSwing{
     public static void main(String[] args)
          JFrame myWindow;
          myWindow = new JFrame();
          myWindow.setSize(300,200);
          myWindow.setTitle("My First Swing Application");
          myWindow.setVisible(true);
          System.exit(0);
}when I run this program
neo@tathagata:~/Java Progs$ java helloSwingThis is the error I am getting
Exception in thread "main" java.awt.AWTError: Cannot load AWT toolkit: gnu.java.awt.peer.gtk.GtkToolkit
   at java.awt.Toolkit.getDefaultToolkit() (/usr/lib/libgcj.so.6.0.0)
   at java.awt.EventQueue.invokeLater(java.lang.Runnable) (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.SwingUtilities.invokeLater(java.lang.Runnable) (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.RepaintManager.addInvalidComponent(javax.swing.JComponent) (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.JComponent.revalidate() (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.JComponent.setOpaque(boolean) (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.JPanel.JPanel(java.awt.LayoutManager, boolean) (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.JPanel.JPanel() (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.JRootPane.createGlassPane() (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.JRootPane.getGlassPane() (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.JRootPane.JRootPane() (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.JFrame.createRootPane() (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.JFrame.getRootPane() (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.JFrame.frameInit() (/usr/lib/libgcj.so.6.0.0)
   at javax.swing.JFrame.JFrame() (/usr/lib/libgcj.so.6.0.0)
   at helloSwing.main(java.lang.String[]) (Unknown Source)
   at gnu.java.lang.MainThread.call_main() (/usr/lib/libgcj.so.6.0.0)
   at gnu.java.lang.MainThread.run() (/usr/lib/libgcj.so.6.0.0)
Caused by: java.lang.ClassNotFoundException: gnu.java.awt.peer.gtk.GtkToolkit not found in gnu.gcj.runtime.SystemClassLoader{urls=[file:./,file:./], parent=gnu.gcj.runtime.ExtensionClassLoader{urls=[], parent=null}}
   at java.net.URLClassLoader.findClass(java.lang.String) (/usr/lib/libgcj.so.6.0.0)
   at java.lang.ClassLoader.loadClass(java.lang.String, boolean) (/usr/lib/libgcj.so.6.0.0)
   at java.lang.ClassLoader.loadClass(java.lang.String) (/usr/lib/libgcj.so.6.0.0)
   at java.lang.Class.forName(java.lang.String, boolean, java.lang.ClassLoader) (/usr/lib/libgcj.so.6.0.0)
   at java.lang.Class.forName(java.lang.String) (/usr/lib/libgcj.so.6.0.0)
   at java.awt.Toolkit.getDefaultToolkit() (/usr/lib/libgcj.so.6.0.0)
   ...17 moreIt appears whenever I'm importing some packages it is creating a problem.
With whatever little knowledge of Java I have, I suspect I have messed up in the enviornment variables somewhere.
So here are my
PATH=/usr/local/qt-x11-opensource-src-4.1.0/bin:/usr/local/bin:/usr/local/sbin:/sbin:/usr/sbin:/bin:/usr/bin:/usr/bin/X11:/usr/games:/home/neo/jdk1.3.1_17/bin/:/usr/sbin:/usr/java/jdk1.3.1_17/bin
JAVA_HOME=/usr/java/jdk1.3.1_17Can anybody suggest me an easy link where classpath is explained?
I'm am helpless, coz if this is not getting fixed I need to go back to Windoz ..
leaving Ubuntu, which would be really painful.
Please help. Thanks in Advance.

Cool, I glad it's working. And thanks for the kind words (although
your link sent me some sort of Introduction page, I eventually found
"Tatha's blog").
Now all I have to do is get my setup correct. Also 1.5, also Ubuntu.
I screwed something up when I installed Netbeans, and couldn't
understand how the Debian people have set things up. I just type the
executable's path at the command line (easy with *nix) or let Eclipse
just do the right thing.
Cheers,
Peter

Can I draw *.bmp, *.png in java.awt.canvas ?

In paint method of my program, I get image from Toolkit like this:
public class CanCanvas extends Canvas{
//In loadImage method
Toolkit.getDefaultToolkit().getImage(
                    getClass().getClassLoader().getResource(
                              resource.getString("bg.jpg")));
//.... In paint method
if (image != null && image.size() > 0) {
               for (int j = 0; j < image.size(); j++) {
                    Image image1 = (Image) image.elementAt(j);
                    Rectangle rectangle = (Rectangle) imgLocation.elementAt(j);
                    g.drawImage(image1, rectangle.x, offset + rectangle.y,
                              rectangle.width, rectangle.height, null);
                    i = i <= rectangle.y + rectangle.height + 7 ? rectangle.y
                              + rectangle.height + 7 : i;But there is something very strange, if my image is *.jpg or *.gif, it runs ok, otherwise -*.bmp, *.png-, it can't draw the image.
Would anyone tell me why ? Is the reason java.awt.canvas ?
Thanks in advance ^ ^

If you'd bother to read the documentation of the methods you're using, you'd know:
http://java.sun.com/j2se/1.4.2/docs/api/java/awt/Toolkit.html#getImage(java.lang.String)
Returns an image which gets pixel data from the specified file, whose format can be either GIF, JPEG or PNG.

Problems with awt.Toolkit on Tomcat

Hello! I'm trying to get the Default Toolkit (java.awt.Toolkit.getDefaultToolkit() ) to determine the scrren size of the client, and Tomcat keeps throwing an Exception - now it's the website's Tomcat and the one on my localhost - there it worked.. Is there another way to determine the client's screen size in JSP (not JavaScript!)?? Thanx!

first, the previous poster was right - learn how these protocols are interacting before you try something like you want to do - and they're right, you can't use the AWT toolkit to find out ANYTHING about the client.
HTTP is stateless. so it's like this:
browser request -> your code on server, jsp completely exeutes, generates html -> html PLAIN old html goes to the browser. in that order. no exceptions. ergo, all your code has executed once the browser starts getting data (buffers on the server not withstanding).
As to why you're getting the exception, the server you are trying to run it on is most likely running in a mode called "headless", that is, there is no windowing api available to the JVM, so any awt calls will fail anyway. It works on your box because you are probably running a full windowing os, such as windows or Linux with gnome or kde. it just happens to return the correct screen size because that's the screen size of your screen, not the screen of the browser that it's outputting to. (try running your code locally and making your browser window small, you'll be dismayed that the rendered HTML is not the "right" size - because the screen size call was based on your resolution, NOT the size of the requesting browser window.
if the last 2 sentences don't make sense, re-read them until they do.
best of luck, sorry you're learing these frustrating lessons this way.

Java.awt availability in CDC Toolkit ?

Hi guys and girls,
I've just tried out the Sun Java Toolkit for CDC 1.0 .. I tried making a simple app which uses awt components, such as Frame, Label, Button .. but the Label and Button just wont compile. I always thought that CDC has all the lib for the j2se's java.awt.
Quoted from CDC FAQ :
CDC currently supports three profiles. Foundation Profile provides basic application support APIs without any additional support for GUIs. Personal Basis Profile includes all of the APIs contained in Foundation Profile and adds support for lightweight AWT GUI components and the xlet application model. Personal Profile includes all of the APIs contained in Personal Basis Profile and adds support for full AWT compatibility and the applet application model.
Do i miss something .. ? Please help pointing out for me ..
I understand that there's swing from the AGui. So i tried making a new project with a simple class containing a simple JFrame, containing a JPanel which contains a button, which can be clicked to trigger a message type JOptionPane. But when the JOptionPane appears, it fills up the entire screen, i dont quite understand what is wrong.
Here's the code :
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class HelloWorld {
      * @param args
     public static void main(String[] args) {
          final JFrame frame = new JFrame("Ahiak");
          final JPanel panel = new JPanel(new FlowLayout());
          JButton but = new JButton("Click Me !");
          panel.add(but);
          frame.getContentPane().add(panel);
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}Please show some compassion and click the reply button, lol -_-

I don't know about swing, but you can try using AWT and compile it with J2SE (set compliance to 1.4). The jar file should work on your mobile device with Personal Profile.

DataFlavors in java.awt.datatransfer

Hello
I'm in the process of developing an application that manages the clipboard . The program runs in the "SystemTray" using the java Toolkit , on the user's request the application takes the content of the clipboard and sends it to other computers on the network that has the program and puts them in the client;s clipboard , that way the user only has to use the copy/paste functions much like if the data was resided on the computer .So far i was able to manage for pictures ,plain text and String selections , the problem is in File selections , now the "JavaFileList" flavor returns an "ArrayList" containing a String representation of the path of each file , which makes it impossible for the client to copy the content to this clipboard unless he has the same directory naming on his computer.I tried implementing a different File Selection that takes each single file as an instance of java.io.File and adds them to a vector , but still the program returns an "ArrayList" with the paths as strings ,i wanted to know should I write a new DataFlavor different than the "JavaFileListFlavor" or the error resides some where else because it worked for images , done by implementing an ImageSelection class much like the StringSelection already given by java.awt.datatransfer.
Thank you for your collaboration.
Edited by: Wafic1 on May 14, 2009 8:36 PM

Strings and arrays are actually stored in the clipboard in their binary representation - and thus they can be copied easily. Files however exist as a pointer to the actual file content on the hard disk. If you copy the reference to a 4GB iso to the clipboard, you will obviously not copy the entire file.
If you want to copy the file, you will have to do it manually. You can either store small files in the clipboard by reading them to byte[]s (implementing your own data flavor), or you can use URIs (if you have some means of the target machine accessing the source machines, such as smb or ftp).
By the way, didn't you already post this question before?

How to use KAWT with "Sun Java Wireless Toolkit 2.3 Beta"?

Hi!
Im new to developing java for mobile devices so all of this is pretty confusing for me. I started with installing suns:s "Wireless Toolkit 2.3 Beta" and it works fine but now I want to use awt classes so I started to look it up and that�s how I found out about kawt. I followed the tutorial at http://www.kawt.de/ and i was able to use it for Java Wireless Toolkit 1.0.4_02 so that it compiled fine and was run able.
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I'd welcome any help
Thanks!

If using the zip install of DSEE, you need to use your own java container to host DSEE. Try downloading the latest Tomcat (http://tomcat.apache.org) and deploying your dscc in it.

Awt.toolkit returns null

Hi all, I've discovered that the awt.toolkit system property returns null on the linux server hosting a java web application am working on. I've listed some of the AWT system properties on the system but the awt.toolkit returns null.
java.awt.graphicsenv: = sun.awt.X11GraphicsEnvironment
java.awt.headless: = ture
awt.toolkit: = null
I really dont know what could be causing this.
This affects all image related proceses (dynamic image creation) that the application does. It outputs the following error message:
java.lang.NoClassDefFoundError
     java.lang.Class.forName0(Native Method)
     java.lang.Class.forName(Class.java:141)
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Any thoughts ?
Cheers

It hs something to do with a missing X11 server/the machine being headless. I faced a similar problem recently.

Can I have my own implementation of java.awt.EventQueue

Hi guys,
Can I "override" the default implementation of java.awt.EventQueue? Some JVM/CVM tricks?
For any tips, Thanks!

I think what you're looking for is EventQueue#push(EventQueue).
public static void main(String[] args) {
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        frame.setContentPane(new JButton("Click Me"));
        frame.setSize(300, 300);
        frame.setLocationRelativeTo(null);
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setVisible(true);
    }

"Cannot load AWT toolkit" - help!

I get the "Cannot load AWT toolkit" error when I try to include awt functionality. Any suggestions?
JAVA_HOME, CLASSPATH and PATH are set...what next?
Thanks!
Regards,
-Rob

The application compiled fine....
"javac xxxx.java"
- no errors
It happens when I try to run it from the command line.
"java xxxx"
- Exception in thread "main" java.awt.AWTError: Cannot load AWT toolkit: gnu.java.awt.peer.gtk.GtkToolkit
Thanks!
-Rob

Java.awt.Toolkit.getScreenSize()

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