Transform a class that implements JPanel into a bean.
I'd to create a bean, from a class that implements JPanel, that in fact is a custom component.
How can I create a bean?
I have absolutely no idea about beans.
What can make beans for me?
I know a lot about the theory of ejb, is this what I need?
I'm quite confused, please make me see the light!!!!!
Thanks.
Hi Daniel!
To answer your question short as possible:
Java -Beans are reusable code - components,
similar to VB Active -X components,
which you can use when developing your own
applications.
Beans can have a graphic user interface, so you
can use builder tools like JBuilder or Beanbox
to show them graphically in a designer.
You can modify them about their properties,
mostly shown in a special property window of a
builder tool.
It's really not very hard to create your own beans,
the only thing you have to do is to pack all the
classes which make the bean into a jar file.
Then you can import the bean with the builder
and it will be shown.
The jar manifest file needs to look like for example:
Manifest-Version: 1.0
Name: BeanClock.class
Java-Bean: True
All the properties are implemented by public property-get
and property-set methods, in order to show them in the property window.
Java is doing that by introspection.
Hope, this makes it a little bit clearer for you!
Similar Messages
-
Can any one change this Applet into a class that extends Jpanel.....
Hi,
I need this applet as a class that extends JPanel, I will be very very thankful to you if any one kindly change this Applet code into a class that extends JApplet.
I will be very thankful to you if some one can reserve few minutes & do this favor early.
Thanks a lot for any help.
My Pong Code
import java.applet.*;
import java.awt.*;
import java.io.*;
import java.awt.event.*;
public class Class1 extends Applet implements Runnable
{ private final int APPLET_WIDTH = 900;
private final int APPLET_HEIGHT = 600;
private int px = 15;
private final int py = 560;
private final int ph = 10;
private final int pw = 75;
private int old_px = px;
private int bx = 450;
private int by = 15;
private final int bh = 20;
private final int bw = 20;
private int move_x = 2;
private int move_y = 2;
private boolean done = false;
Thread t;
private final int delay = 25;
public void init()
{ setBackground(Color.black);
setSize(APPLET_WIDTH, APPLET_HEIGHT);
requestFocus();
addKeyListener(new DirectionKeyListener());
(t = new Thread(this)).start();
public void run() {
try { while((t == Thread.currentThread()) && (done == false)) {
if ((bx < 15) || (bx > APPLET_WIDTH-30)) move_x = -move_x; if ((by < 15) || ((by > APPLET_HEIGHT-60)&& ((px<=bx)&&(bx<=px+pw))))
move_y = -move_y;
if (by > APPLET_HEIGHT)
done = true;
bx = bx + move_x;
by = by + move_y; repaint();
t.sleep(delay);
catch(Exception e) {}
}//end run
/*public void move_paddle(int amount)
old_px = px;
//if (amount > 0)
//if (px <= APPLET_WIDTH-15)
px = px + amount;
//else if (amount < 0)
// if (px >= 15)
px = px + amount;
public void paint(Graphics page)
// page.setColor(Color.black);
// page.drawRect(old_px, py, pw, ph);
page.setColor(Color.blue);
page.drawRect(px, py, pw, ph);
page.setColor(Color.white);
page.drawOval(bx, by, bw, bh);
if ((done == true) && (by > APPLET_HEIGHT))
page.drawString("LOSER!!!", APPLET_WIDTH/2, APPLET_HEIGHT/2);
else if (done == true)
page.drawString("Game Over, Man!", APPLET_WIDTH/2-10, APPLET_HEIGHT/2);
private class DirectionKeyListener implements KeyListener
public void keyPressed (KeyEvent event)
switch (event.getKeyCode())
case KeyEvent.VK_LEFT:
old_px = px;
if (px >=15)
px -=10;
break;
case KeyEvent.VK_RIGHT:
old_px = px;
if (px+pw <= APPLET_WIDTH-15)
px += 10;
break;
case KeyEvent.VK_Q:
done = true;
default:
} //end switch
repaint();
}//end keyPressed
public void keyTyped (KeyEvent event)
public void keyReleased (KeyEvent event)
} //end class
}thank you sir for your advice.
Its not like that I without any attempt, just past code here & asked for its conversion. I spent about 5 hours on it, can say spoil whole day but to no avail. You then just guide me, give some hint so that I do it. I will most probably wanted to do it by myself but asked for help when was just disappointed.
I try to put all init() in default constructor of identical copy of this applet that extends JPanel. Problem.....ball tend to fell but pad not moving. Also out out was not getting ant color input. That was like my best effort.....other tried that I found by search like just do nothing only extend panel OR frame in spite of applet, start applet from within main of another class.... these are few I remember what I tried.
I will be very very thankful to you if you can help/guide me how can I do it. Behavior of the Applet is like a normal PONG game with on pad controlled by arrow keys, & one ball colliding with walls of boundary & falling down.
Thanks a lot again for your attention & time. -
JEditorPane (or subclasses) and a class that extends JPanel
hello to all,
i'm realizing an application with Swing.
i have realized a class that extends JPanel(called "PanelLayer") and, other to draw a ruler as Office 2003, it must contain an other subclass of JPanel (called "PanelLayer") that, in turn, will contain a JEditorPane.
the problem is strange: i should continue in moviment the mouse to look well the JEditorPane (or subclasses)
the URL is a image of the result that i get...
URL : http://phantom89.helloweb.eu/img/img.jpg
codes:
public class Layer extends JPanel implements ComponentListener{
private static final long serialVersionUID = 1L;
private Rectangle2D.Double areaCentrale = new Rectangle2D.Double(100,100,850,1285);
private double larghFoglio = 21.0*50;
private double altFoglio = 29.7*50;
private double zoom = 1.0;
private JScrollPane sp = new JScrollPane(this);
private Rectangle2D.Double posFoglio = new Rectangle2D.Double();
private int lastX,lastY;
private PanelLayer pl;
private Point mouse = null;
private JEditorPane text;
public Layer(PanelLayer pl){
this.setLayout(null);
this.pl = pl;
this.setPreferredSize(new Dimension((int)(40+larghFoglio*zoom), (int)(100+altFoglio*zoom)));
areaCentrale = new Rectangle2D.Double(100*zoom,100*zoom,850*zoom,1285*zoom);
sp.setHorizontalScrollBarPolicy(ScrollPaneConstants.HORIZONTAL_SCROLLBAR_ALWAYS);
sp.setVerticalScrollBarPolicy(ScrollPaneConstants.VERTICAL_SCROLLBAR_ALWAYS);
//try{
text = new JEditorPane();
text.setBounds(50,50,200,200);
this.add(text);
//}catch(IOException e){}
lastX = sp.getHorizontalScrollBar().getValue();
lastY = sp.getVerticalScrollBar().getValue();
this.addComponentListener(this);
this.addMouseListener(this);
this.addMouseMotionListener(this);
public void paintComponent(Graphics g){
if(posFoglio.height + posFoglio.width == 0){
this.posFoglio = new Rectangle2D.Double((this.getWidth()-larghFoglio*zoom)/2,50,larghFoglio*zoom,altFoglio*zoom);
Graphics2D g2d = (Graphics2D)g;
g2d.setPaint(Color.lightGray);
g2d.fillRect(0,0,this.getWidth(),this.getHeight());
g2d.translate((this.getWidth()-larghFoglio*zoom)/2,50);
g2d.setPaint(Color.black);
g2d.draw(new Rectangle2D.Double(0,0,larghFoglio*zoom,altFoglio*zoom));
g2d.setPaint(Color.white);
g2d.fill(new Rectangle2D.Double(1,1,larghFoglio*zoom-1,altFoglio*zoom-1));
g2d.setPaint(Color.blue);
g2d.draw(areaCentrale);
public JScrollPane getJScrollPane(){
return sp;
public Rectangle2D.Double getDimFoglio(){
return this.posFoglio;
public double getCmWidth(){
return larghFoglio*zoom/50+((larghFoglio*zoom/50)%1 <= getIncr() ? 0 : getIncr());
public double getCmHeight(){
return altFoglio*zoom/50+((altFoglio*zoom/50)%1 <= getIncr() ? 0 : getIncr());
public Point getPointMouse(){
return mouse;
public void refresh(){
lastX = sp.getHorizontalScrollBar().getValue();
posFoglio.x = (this.getWidth()-larghFoglio*zoom)/2-lastX;
public double getIncr(){
return zoom/2;
public void mouseClicked(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {}
public void mouseExited(MouseEvent e) {}
public void mousePressed(MouseEvent e) {}
public void mouseReleased(MouseEvent e) {}
public void mouseDragged(MouseEvent e) {}
public void mouseMoved(MouseEvent e) {
mouse = e.getPoint();
mouse.x -= sp.getHorizontalScrollBar().getValue();
mouse.y -= sp.getVerticalScrollBar().getValue();
pl.repaint();
public void componentHidden(ComponentEvent e) {}
public void componentMoved(ComponentEvent e) {
lastX = sp.getHorizontalScrollBar().getValue();
posFoglio.x = (this.getWidth()-larghFoglio*zoom)/2-lastX;
lastY = sp.getVerticalScrollBar().getValue();
posFoglio.y = 50-lastY;
pl.repaint();
public void componentResized(ComponentEvent e) {
this.repaint();
pl.repaint();
public void componentShown(ComponentEvent e) {}
public class PanelLayer extends JPanel implements MouseWheelListener,MouseInputListener{
private static final long serialVersionUID = 1L;
private Layer layer;
private JScrollPane sp = null;
private boolean visualizzaMouse = false;
public PanelLayer(){
this.setLayout(null);
layer = new Layer(this);
layer.addMouseListener(this);
layer.addMouseMotionListener(this);
public void paintComponent(Graphics g){
if(layer.getDimFoglio().getWidth()+layer.getDimFoglio().getHeight() == 0){
layer.setSize(50,50);
if(sp == null){
sp = layer.getJScrollPane();
sp.addMouseWheelListener(this);
sp.setBounds(30,30,this.getWidth()-30,this.getHeight()-30);
this.add(sp);
}else{
layer.refresh();
sp.setBounds(30,30,this.getWidth()-30,this.getHeight()-30);
Graphics2D g2d = (Graphics2D)g;
g2d.setPaint(new Color(153,255,153));
g2d.fill(new Rectangle2D.Double(0,0,this.getWidth(),30));
g2d.fill(new Rectangle2D.Double(0,0,30,this.getHeight()));
g2d.setPaint(Color.black);
g2d.drawLine(0,0,this.getWidth(),0);
g2d.drawLine(0,30,this.getWidth(),30);
g2d.drawLine(0,0,0,this.getHeight());
g2d.drawLine(30,0,30,this.getHeight());
for(double i=0,j=0;i<=layer.getCmWidth();i+=layer.getIncr(),j++){
if(j%2==0){
g2d.drawLine((int)(layer.getDimFoglio().x+31+i*50), 15,(int)(layer.getDimFoglio().x+31+i*50), 30);
g2d.drawString(String.valueOf((int)(j/2)), (float)(layer.getDimFoglio().x+31+i*50), 13);
}else{
g2d.drawLine((int)(layer.getDimFoglio().x+31+i*50), 22,(int)(layer.getDimFoglio().x+31+i*50), 30);
for(double i=0,j=0;i<=layer.getCmHeight();i+=layer.getIncr(),j++){
if(j%2==0){
g2d.drawLine(15, (int)(layer.getDimFoglio().y+31+i*50),30,(int)(layer.getDimFoglio().y+31+i*50));
g2d.drawString(String.valueOf((int)(j/2)),5,(float)(layer.getDimFoglio().y+31+i*50));
}else{
g2d.drawLine(22, (int)(layer.getDimFoglio().y+31+i*50),30,(int)(layer.getDimFoglio().y+31+i*50));
if((layer.getPointMouse() != null)&&(visualizzaMouse)){
g2d.drawLine(layer.getPointMouse().x+30,0,layer.getPointMouse().x+30,30);
g2d.drawLine(0,layer.getPointMouse().y+30,30,layer.getPointMouse().y+30);
g2d.setPaint(new Color(153,255,153));
g2d.fillRect(1,1,29,29);
int largh = layer.getJScrollPane().getVerticalScrollBar().getWidth();
g2d.fillRect(this.getWidth()-largh, 1, largh, 29);
g2d.fillRect(1, this.getHeight()-largh, 29, largh);
public void mouseWheelMoved(MouseWheelEvent e) {
JScrollBar vsb = layer.getJScrollPane().getVerticalScrollBar();
vsb.setValue(vsb.getValue()+20*e.getWheelRotation());
public void refresh(){
if((layer != null)&&(sp != null)){
layer.setSize(this.getWidth()-30,this.getHeight()-30);
sp.setViewportView(layer);
this.repaint();
public void mouseClicked(MouseEvent e) {}
public void mouseEntered(MouseEvent e) {
visualizzaMouse = true;
repaint();
public void mouseExited(MouseEvent e) {
visualizzaMouse = false;
repaint();
public void mousePressed(MouseEvent e) {}
public void mouseReleased(MouseEvent e) {}
public void mouseDragged(MouseEvent e) {}
public void mouseMoved(MouseEvent e) {}
}(my english isn't very good)Don't really understand what the posted code does and I can't execute the code so I don't have much to offer.
But I did notice that you don't invoke super.paintComponent(...) which means you may have garbage being painted on the panels.
If you need further help then you need to create a "Short, Self Contained, Compilable and Executable, Example Program (SSCCE)", that demonstrates the incorrect behaviour.
http://homepage1.nifty.com/algafield/sscce.html -
Closing a class that extends JPanel
Hi, i have a class that extends JPanel(lets call it class A). In that class, if the user click the logout button, i want class A to close and display class B that extends JFrame. right now, i am able to call class B, but i cannot close class A.
I uses remove() to close class A, but it doesnt work... could u tell me what to do??
I put this code in class A...
if (e.getSource() == logoutButton) {
remove(this);
new Rest_Login1();
String [] ar = null;
Rest_Login1.main(ar);
} Thxso i want to remove the CustomerPanel3 and display the Rest_Login1...
some of my code look like this.
thx
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class CustomerPanel3 extends JPanel implements ActionListener
// some JButton, JLabel n etc
public void actionPerformed (ActionEvent e)
if (e.getSource() == logoutButton) {
remove(this);
new Rest_Login1();
String [] ar = null;
Rest_Login1.main(ar);
public class Rest_Login1 {
public static void main(String args[])
JFrame login1 = new JFrame("Login User Interface");
JFrame.setDefaultLookAndFeelDecorated(true);
RestaurantLogin userpan = new RestaurantLogin();
login1.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
login1.setSize(600, 250);
login1.setLocation(230,192);
login1.getContentPane().add(userpan);
login1.setVisible(true);
} -
Serializing a class that implements the Singleton pattern
Hello,
I am relatively new to Java and especially to serialization so the answer to this question might be obvious, but I could not make it work event though I have read the documentation and the article "Using XML Encoder" that was linked from the documentation.
I have a class that implements the singleton pattern. It's definition is as follows:
public class JCOption implements Serializable {
private int x = 1;
private static JCOption option = new JCOption();
private JCOption() {}
public static JCOption getOption() { return option; }
public int getX() { return x; }
public void setX(int x) { this.x = x; }
public static void main(String args[]) throws IOException {
JCOption opt = JCOption.getOption();
opt.setX(10);
XMLEncoder encoder = new XMLEncoder(new BufferedOutputStream(new FileOutputStream("Test.xml")));
encoder.setPersistenceDelegate(opt.getClass(), new JCOptionPersistenceDelegate());
encoder.writeObject(opt);
encoder.close();
}Since this class does not fully comply to the JavaBeans conventions by not having a public no-argument constructor, I have create a class JCOptionPersistenceDelegate that extends the PersistenceDelegate. The implementation of the instantiate method is as follows:
protected Expression instantiate(Object oldInstance, Encoder out) {
Expression expression = new Expression(oldInstance, oldInstance.getClass(), "getOption", new Object[]{});
return expression;
}The problem is that the resulting XML file only contains the following lines:
<java version="1.5.0_06" class="java.beans.XMLDecoder">
<object class="JCOption" property="option"/>
</java> so there is no trace of the property x.
Thank you in advance for your answers.How about this:
import java.beans.DefaultPersistenceDelegate;
import java.beans.Encoder;
import java.beans.Expression;
import java.beans.Statement;
import java.beans.XMLEncoder;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
public class JCOption {
private int x = 1;
private static JCOption option = new JCOption();
private JCOption() {}
public static JCOption getOption() { return option; }
public int getX() { return x; }
public void setX(int x) { this.x = x; }
public static void main(String args[]) throws IOException {
JCOption opt = JCOption.getOption();
opt.setX(10);
ByteArrayOutputStream os = new ByteArrayOutputStream();
XMLEncoder encoder = new XMLEncoder( os );
encoder.setPersistenceDelegate( opt.getClass(), new JCOptionPersistenceDelegate() );
encoder.writeObject(opt);
encoder.close();
System.out.println( os.toString() );
class JCOptionPersistenceDelegate extends DefaultPersistenceDelegate {
protected Expression instantiate(Object oldInstance, Encoder out) {
return new Expression(
oldInstance,
oldInstance.getClass(),
"getOption",
new Object[]{} );
protected void initialize( Class<?> type, Object oldInstance, Object newInstance, Encoder out ) {
super.initialize( type, oldInstance, newInstance, out );
JCOption q = (JCOption)oldInstance;
out.writeStatement( new Statement( oldInstance, "setX", new Object[] { q.getX() } ) );
} Output:
<?xml version="1.0" encoding="UTF-8"?>
<java version="1.5.0_06" class="java.beans.XMLDecoder">
<object class="JCOption" property="option">
<void property="x">
<int>10</int>
</void>
</object>
</java> -
Reflect the class that implements Runnable
Hi,
I am implementing the reflection of the class that implements Runnable. In order to start a new thread I am trying to invoke "start()" method ( which is obviously not defined my class ) and I therefore I am getting "java.lang.NoSuchMethodException".
I am wondering is it possible at all to start a new thread on a reflected class?
thanks in advance.
{ Class refClass = Class.forName(className);
String methodName = "start";
Class[] types = new Class[1];
types[0] = Class.forName("java.util.HashMap");
Constructor cons = refClass.getConstructor(types);
Object[] params = new Object[5];
params[0] = new HashMap();
Method libMethod = refClass.getMethod(methodName, null);
libMethod.invoke(objType, null); }Well, if we knew what it meant to "start a thread on a class" we could probably figure out how to "start a thread on a reflected class". If we knew what a "reflected class" was, that is.
In other words, it would help if you rephrased your question using standard terminology (and also explained why you want to do whatever it is you want to do).
But let's guess for now: If you have an object which implements Runnable then you start a thread to run that object like this:
Runnable r = // some object which implements Runnable
new Thread(r).start();Not what you wanted? Go ahead and clarify then. -
HELP?! a class that implements ..... : java.util.Vector
My instructions say this:
In the constructor, create the collection object (Since java.util.List is an interface, you will need to instantiate a class that implements this interface: java.util.Vector or java.util.LinkedList or java.util.ArrayList).
I know, this IS a homework assignment - I am not sure how to go about this. I DO have code so far up to this point, can anyone help?
import dLibrary.*;
import java.awt.Color;
* @author Rob
* @version 8/18/03
public class PhrasesII extends A3ButtonHandler
private A3ButtonWindow win;
private ATextField stringAcceptor;
private ALabel listOstrings;
private ALabel inputString;
private ALabel status;
private java.awt.List display;
private java.util.List collection;
public PhrasesII()
win = new A3ButtonWindow(this);
stringAcceptor= new ATextField (50,420,200,25);
stringAcceptor.place(win);
listOstrings = new ALabel(100, 10, 100, 380);
listOstrings.setFontSize(10);
listOstrings.setText("List of Strings:");
listOstrings.place(win);
inputString = new ALabel(50,400,200,25);
inputString.setFontSize(10);
inputString.setText("Input String:");
inputString.place(win);
display = new java.awt.List();
display.setLocation(200, 100);
display.setSize(200, 250);
display.setBackground(Color.lightGray);
win.add(display, 0);
win.setLeftText("Save");
win.setMidText("Display");
win.setRightText("Discard");
win.repaint();
public void leftAction()
public void midAction()
public void rightAction()I am getting a " can't resolve symbol" when I do thisYou have to either import java.util.ArrayList or specify it fully, e.g., "new java.util.ArrayList()".
Is that the line that is causing you problems? The error message should give the line number.
my instructions also say I have to use "interface
java.util.List when declaring your reference" so I am
confused about using "= new ArrayList();"What they're saying is that you want code like this:
private java.util.List frogs; // this is the reference declaration
//... later on...
frogs = new java.util.ArrayList(); // this isn't a declarationWhat this means is that when you declare a field or variable, you should declare its type to be an interface.
But when you actually instantiate a value for that variable, then you should use a concrete class that implements that interface. (You have to; interfaces can't be instantiated.)
This is good programming style for reasons I don't have the space to explain here. -
Modifying a Class that implements Serializable
I have a class LDAPUser
import java.io.*;
public class LDAPUser implements java.io.Serializable{
private java.lang.String name;
private java.lang.String userID;
private java.lang.String associateNumber;
public LDAPUser() {
super();
public boolean equals(Object o) {
if (o == this)
return true;
if (!(o instanceof LDAPUser))
return false;
return (((LDAPUser)o).getAssociateNumber().equals(this.getAssociateNumber()));
public java.lang.String getAssociateNumber() {
if(associateNumber == null){
return getUserID();
return associateNumber;
public java.lang.String getName() {
return name;
public java.lang.String getUserID() {
return userID;
public void setAssociateNumber(java.lang.String newAssociateNumber) {
associateNumber = newAssociateNumber;
public void setName(java.lang.String newName) {
name = newName;
public void setUserID(java.lang.String newUserID) {
userID = newUserID;
It works fine.
I needed to add functionality to it. These were the modifications.
private java.lang.String distinguishedName;
private boolean validUser;
public java.lang.String getDistinguishedName() {
return distinguishedName;
public boolean isValidUser() {
return validUser;
public void setDistinguishedName(java.lang.String newDistinguishedName) {
distinguishedName = newDistinguishedName;
public void setValidUser(boolean newValidUser) {
validUser = newValidUser;
I am using visual age for java and in the Test environment the changes work fine.
When I promote the changes to our application server (websphere) the changes are not there. I get a method not found error and though trial and error have identified that the server is not actually using the class from the jar. I have removed any other occurences of the class from the server.
My question is if I change a Serializable class how do I make those changes take affect (thorough better coding) and for right now, where is this "old instance" of my class coming from and how do I get rid of it.
Thanks in Advance,
Jason GrieveIf the server is running than the class might be already loaded through the class loader, so it wont be load again.
this unless you use hot deployment, which you have to figure how it is being handled in your srver.
Doron -
Abstract Class that implements Comparable
I am trying to understand how a comparable interface works with an abstract class. Any help is greatly appreciated.
I have a class ClassA defined as follows:
public abstract class ClassA implements Comparable I have a method, compareTo(..), within ClassA as follows:
public int compareTo(Object o) I have a sub-class ClassB defined as follows:
public class ClassB extends ClassAI am receiving a compile error:
Class must implement the inherited abstract method packagename.ClassA.compareTo(Object)
Should or can the compareTo be abstract in ClassA and executed in ClassB? Just not sure how this works.???? if you are inheriting from an abstract class your subclass must implement methods that were declared in the parent (abstract) class but not implemented
When in doubt, refer to the Java Language Specification.. -
Xml Serializing a class that extends JPanel
Alright I am getting an Exception saying java.
java.lang.reflect.InvocationTargetException
Continuing ...
java.lang.Exception: XMLEncoder: discarding statement XMLEncoder.writeObject(JpanelScreen);
Continuing ...
is anyone familiar with this... It ocurrs when I try to Serialize my class object that extends JPanel...any examples of how to do this?
try {
java.beans.XMLEncoder out = new java.beans.XMLEncoder( new BufferedOutputStream( new java.io.FileOutputStream(getFilename())));
out.writeObject(Screen);
out.close();
}catch (Exception exc) {System.err.println(exc.getMessage());} -
Question about methods in a class that implements Runnable
I have a class that contains methods that are called by other classes. I wanted it to run in its own thread (to free up the SWT GUI thread because it appeared to be blocking the GUI thread). So, I had it implement Runnable, made a run method that just waits for the thread to be stopped:
while (StopTheThread == false)
try
Thread.sleep(10);
catch (InterruptedException e)
//System.out.println("here");
(the thread is started in the class constructor)
I assumed that the other methods in this class would be running in the thread and would thus not block when called, but it appears the SWT GUI thread is still blocked. Is my assumption wrong?powerdroid wrote:
Oh, excellent. Thank you for this explanation. So, if the run method calls any other method in the class, those are run in the new thread, but any time a method is called from another class, it runs on the calling class' thread. Correct?Yes.
This will work fine, in that I can have the run method do all the necessary calling of the other methods, but how can I get return values back to the original (to know the results of the process run in the new thread)?Easy: use higher-level classes than thread. Specifically those found in java.util.concurrent:
public class MyCallable implements Callable<Foo> {
public Foo call() {
return SomeClass.doExpensiveCalculation();
ExecutorService executor = Executors.newFixedThreadPool();
Future<Foo> future = executor.submit(new MyCallable());
// do some other stuff
Foo result = future.get(); // get will wait until MyCallable is finished or return the value immediately when it is already done. -
Importing classes that implement jsp tags
I was making a custom JSP tag library. The tag functionality was implemented in
a class called, lets cay ClassA. I made the tld file and put it under the WEB-INF
directory. The class which implemented the functionality was placed under WEB-INF/classes
directory. I had the imported the tag library using the taglib directive. I was
getting an error which said "cannot resolve symbol". But when I in the JSP file
I imported the class file which implemented the taglib functionality the error
vanished. Is it necessary to import the class files even if the taglib is imported.
The documentation does not say so. Or is there some configuration I have to make.
I think was a side effect of the .jsp changing redeploys the web app in 6.0.
When the web app was redeployed your directory structure was reread and thus
it found your .tld.
Sam
"bbaby" <[email protected]> wrote in message
news:3b422db7$[email protected]..
>
> I was making a custom JSP tag library. The tag functionality was
implemented in
> a class called, lets cay ClassA. I made the tld file and put it under the
WEB-INF
> directory. The class which implemented the functionality was placed under
WEB-INF/classes
> directory. I had the imported the tag library using the taglib directive.
I was
> getting an error which said "cannot resolve symbol". But when I in the JSP
file
> I imported the class file which implemented the taglib functionality the
error
> vanished. Is it necessary to import the class files even if the taglib is
imported.
> The documentation does not say so. Or is there some configuration I have
to make.
>
>
-
"Bean Class Must Implement X" message, but bean class does implement X
When trying to deploy an .ear file on WebLogic 9.0 that contains an MDB EJB, I get a message like the following:
In EJB ITS-MDB(Application: ITSNO,
EJBComponent: ITSMDB.jar), the bean class must implement
its.common.TelnetMessageListener. '
The ITS-MDB EJB class (its.mdb.TelnetMessageListenerImpl) referenced in ejb-jar.xml DOES implement its.common.TelnetMessageListener, and both .class files exist in the same .jar file.
(The TelnetMessageListener interface extends javax.ejb.MessageDrivenBean.)
This .ear deploys without a problem on Oracle's OC4J and IBM's Websphere, so it appears that there is some Weblogic peculiarity (a bug, a different spec interpretation, etc.) causing the problem.
This problem is happening on Weblogic 9.0 using Java 1.5.0_03 on Windows XP.
Any ideas why this might be happening?Thanks for the suggestion, Rob.
I checked to ensure that no out-dated TelnetMessageListenerImpl and TelnetMessageListener were being used. It looks like I am not using older versions.
I first checked the classpath specified by the log, and did not see anywhere in there that would contain either of these classes.
To be sure, I then decided to remove each class from the jar file and attempt to deploy it. If it succeeded, that would mean there was some other version of that file on the classpath.
I first removed TelnetMessageListenerImpl from ITSMDB.jar, and then tried deploying it. As expected, I received the following message:
Unable to deploy EJB: C:\bea\user_projects\domains\domain_good\.\servers\AdminServer\tmp\_WL_user\ITSNOMinus\fvdi9g\ITSMDB.jar from ITSMDB.jar:
Unable to load a class specified in your ejb-jar.xml: its.mdb.TelnetMessageListenerImpl
at weblogic.ejb20.deployer.EJBModule.prepare(EJBModule.java:371)
at weblogic.application.internal.flow.ModuleListenerInvoker.prepare(ModuleListenerInvoker.java:90)
I then replaced TelnetMessageListenerImpl and attempted to remove TelnetMessageLister. I got a slightly different (but essentially the same) error:
java.lang.NoClassDefFoundError: oracle/wireless/its/common/TelnetMessageListener
at java.lang.ClassLoader.defineClass1(Native Method)
at java.lang.ClassLoader.defineClass(ClassLoader.java:620)
at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:124)
at weblogic.utils.classloaders.GenericClassLoader.defineClass(GenericClassLoader.java:302)
at weblogic.utils.classloaders.GenericClassLoader.findLocalClass(GenericClassLoader.java:255)
at weblogic.utils.classloaders.GenericClassLoader.findClass(GenericClassLoader.java:223)
at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
at java.lang.ClassLoader.loadClass(ClassLoader.java:251)
at weblogic.utils.classloaders.GenericClassLoader.loadClass(GenericClassLoader.java:158)
at weblogic.ejb20.deployer.EJBModule.setupEJBToImplClassDependencies(EJBModule.java:1396)
Here is the exception stack I get will the original ITSNO deployment:
####<Sep 20, 2005 11:20:57 AM PDT> <Info> <Deployer> <jrozier-pc> <AdminServer> <[STANDBY] ExecuteThread: '5' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1127240457892> <BEA-149059> <Module ITSMDB.jar of application ITSNO is transitioning from STATE_NEW to STATE_PREPARED on server AdminServer.>
####<Sep 20, 2005 11:20:58 AM PDT> <Info> <EJB> <jrozier-pc> <AdminServer> <[STANDBY] ExecuteThread: '5' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1127240458002> <BEA-010008> <EJB Deploying file: ITSMDB.jar>
####<Sep 20, 2005 11:20:58 AM PDT> <Info> <Deployer> <jrozier-pc> <AdminServer> <[STANDBY] ExecuteThread: '5' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1127240458080> <BEA-149061> <Module ITSMDB.jar of application ITSNO failed to transition from STATE_NEW to STATE_PREPARED on server AdminServer.>
####<Sep 20, 2005 11:20:58 AM PDT> <Info> <Deployer> <jrozier-pc> <AdminServer> <[STANDBY] ExecuteThread: '5' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1127240458080> <BEA-149059> <Module ITSRA.rar of application ITSNO is transitioning from STATE_PREPARED to STATE_NEW on server AdminServer.>
####<Sep 20, 2005 11:20:58 AM PDT> <Info> <Deployer> <jrozier-pc> <AdminServer> <[STANDBY] ExecuteThread: '5' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1127240458111> <BEA-149060> <Module ITSRA.rar of application ITSNO successfully transitioned from STATE_PREPARED to STATE_NEW on server AdminServer.>
####<Sep 20, 2005 11:20:58 AM PDT> <Error> <Deployer> <jrozier-pc> <AdminServer> <[STANDBY] ExecuteThread: '5' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1127240458158> <BEA-149265> <Failure occured in the execution of deployment request with ID '1127240456080' for task '0'. Error is: 'weblogic.application.ModuleException: Exception preparing module: EJBModule(ITSMDB.jar)
Unable to deploy EJB: C:\bea\user_projects\domains\domain_good\.\servers\AdminServer\tmp\_WL_user\ITSNO\x5gd0k\ITSMDB.jar from ITSMDB.jar:
In EJB ITS-MDB(Application: ITSNO, EJBComponent: ITSMDB.jar), the bean class must implement its.common.TelnetMessageListener.
weblogic.application.ModuleException: Exception preparing module: EJBModule(ITSMDB.jar)
Unable to deploy EJB: C:\bea\user_projects\domains\domain_good\.\servers\AdminServer\tmp\_WL_user\ITSNO\x5gd0k\ITSMDB.jar from ITSMDB.jar:
In EJB ITS-MDB(Application: ITSNO, EJBComponent: ITSMDB.jar), the bean class must implement its.common.TelnetMessageListener.
at weblogic.ejb20.deployer.EJBModule.prepare(EJBModule.java:371)
at weblogic.application.internal.flow.ModuleListenerInvoker.prepare(ModuleListenerInvoker.java:90)
at weblogic.application.internal.flow.DeploymentCallbackFlow$1.next(DeploymentCallbackFlow.java:318)
at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:26)
at weblogic.application.internal.flow.DeploymentCallbackFlow.prepare(DeploymentCallbackFlow.java:53)
at weblogic.application.internal.flow.DeploymentCallbackFlow.prepare(DeploymentCallbackFlow.java:43)
at weblogic.application.internal.BaseDeployment$1.next(BaseDeployment.java:615)
at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:26)
at weblogic.application.internal.BaseDeployment.prepare(BaseDeployment.java:236)
at weblogic.application.internal.DeploymentStateChecker.prepare(DeploymentStateChecker.java:147)
at weblogic.deploy.internal.targetserver.AppContainerInvoker.prepare(AppContainerInvoker.java:61)
at weblogic.deploy.internal.targetserver.operations.ActivateOperation.createAndPrepareContainer(ActivateOperation.java:191)
at weblogic.deploy.internal.targetserver.operations.ActivateOperation.doPrepare(ActivateOperation.java:84)
at weblogic.deploy.internal.targetserver.operations.AbstractOperation.prepare(AbstractOperation.java:197)
at weblogic.deploy.internal.targetserver.DeploymentManager.handleDeploymentPrepare(DeploymentManager.java:724)
at weblogic.deploy.internal.targetserver.DeploymentManager.prepareDeploymentList(DeploymentManager.java:1137)
at weblogic.deploy.internal.targetserver.DeploymentManager.handlePrepare(DeploymentManager.java:224)
at weblogic.deploy.internal.targetserver.DeploymentServiceDispatcher.prepare(DeploymentServiceDispatcher.java:109)
at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer.doPrepareCallback(DeploymentReceiverCallbackDeliverer.java:166)
at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer.access$100(DeploymentReceiverCallbackDeliverer.java:12)
at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer$2.run(DeploymentReceiverCallbackDeliverer.java:54)
at weblogic.work.ServerWorkManagerImpl$WorkAdapterImpl.run(ServerWorkManagerImpl.java:518)
at weblogic.work.ExecuteThread.execute(ExecuteThread.java:207)
at weblogic.work.ExecuteThread.run(ExecuteThread.java:179)
In EJB ITS-MDB(Application: ITSNO, EJBComponent: ITSMDB.jar), the bean class must implement its.common.TelnetMessageListener.
at weblogic.ejb20.deployer.MessageDrivenBeanInfoImpl.initializeOnMessageMethodInfo(MessageDrivenBeanInfoImpl.java:593)
at weblogic.ejb20.deployer.MessageDrivenBeanInfoImpl.<init>(MessageDrivenBeanInfoImpl.java:346)
at weblogic.ejb20.deployer.BeanInfoImpl.createBeanInfoImpl(BeanInfoImpl.java:551)
at weblogic.ejb20.deployer.MBeanDeploymentInfoImpl.initializeBeanInfos(MBeanDeploymentInfoImpl.java:597)
at weblogic.ejb20.deployer.MBeanDeploymentInfoImpl.<init>(MBeanDeploymentInfoImpl.java:221)
at weblogic.ejb20.deployer.EJBDeployer.prepare(EJBDeployer.java:1165)
at weblogic.ejb20.deployer.EJBModule.prepare(EJBModule.java:344)
at weblogic.application.internal.flow.ModuleListenerInvoker.prepare(ModuleListenerInvoker.java:90)
at weblogic.application.internal.flow.DeploymentCallbackFlow$1.next(DeploymentCallbackFlow.java:318)
at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:26)
at weblogic.application.internal.flow.DeploymentCallbackFlow.prepare(DeploymentCallbackFlow.java:53)
at weblogic.application.internal.flow.DeploymentCallbackFlow.prepare(DeploymentCallbackFlow.java:43)
at weblogic.application.internal.BaseDeployment$1.next(BaseDeployment.java:615)
at weblogic.application.utils.StateMachineDriver.nextState(StateMachineDriver.java:26)
at weblogic.application.internal.BaseDeployment.prepare(BaseDeployment.java:236)
at weblogic.application.internal.DeploymentStateChecker.prepare(DeploymentStateChecker.java:147)
at weblogic.deploy.internal.targetserver.AppContainerInvoker.prepare(AppContainerInvoker.java:61)
at weblogic.deploy.internal.targetserver.operations.ActivateOperation.createAndPrepareContainer(ActivateOperation.java:191)
at weblogic.deploy.internal.targetserver.operations.ActivateOperation.doPrepare(ActivateOperation.java:84)
at weblogic.deploy.internal.targetserver.operations.AbstractOperation.prepare(AbstractOperation.java:197)
at weblogic.deploy.internal.targetserver.DeploymentManager.handleDeploymentPrepare(DeploymentManager.java:724)
at weblogic.deploy.internal.targetserver.DeploymentManager.prepareDeploymentList(DeploymentManager.java:1137)
at weblogic.deploy.internal.targetserver.DeploymentManager.handlePrepare(DeploymentManager.java:224)
at weblogic.deploy.internal.targetserver.DeploymentServiceDispatcher.prepare(DeploymentServiceDispatcher.java:109)
at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer.doPrepareCallback(DeploymentReceiverCallbackDeliverer.java:166)
at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer.access$100(DeploymentReceiverCallbackDeliverer.java:12)
at weblogic.deploy.service.internal.targetserver.DeploymentReceiverCallbackDeliverer$2.run(DeploymentReceiverCallbackDeliverer.java:54)
at weblogic.work.ServerWorkManagerImpl$WorkAdapterImpl.run(ServerWorkManagerImpl.java:518)
at weblogic.work.ExecuteThread.execute(ExecuteThread.java:207)
at weblogic.work.ExecuteThread.run(ExecuteThread.java:179)
>
####<Sep 20, 2005 11:20:58 AM PDT> <Warning> <Deployer> <jrozier-pc> <AdminServer> <[STANDBY] ExecuteThread: '5' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1127240458252> <BEA-149004> <Failures were detected while initiating distribute task for application 'ITSNO'.>
####<Sep 20, 2005 11:20:58 AM PDT> <Warning> <Deployer> <jrozier-pc> <AdminServer> <[STANDBY] ExecuteThread: '5' for queue: 'weblogic.kernel.Default (self-tuning)'> <<WLS Kernel>> <> <> <1127240458252> <BEA-149078> <Stack trace for message 149004
There are a few other updates since my first post as well:
(1) I get the same message when I try to deploy just ITSMDB.jar as an application as I do when I try to deploy my ITSNO.ear (which contains both an RA and the MDB).
(2) This same application now also works on JBoss. (I had to add a jboss.xml to tell the MDB about the RA.)
(3) I fixed the ejb-jar.xml container-transaction element to refer to ITS-MDB (with a dash) instead of ITS_MDB (with an underscore). (This fix goes to show that some containers are more forgiving than others--OC4J and Websphere did not complain about it, but JBoss gave an error message and would not deploy until this was fixed.) -
Example class that implements Serializable interface
Dear,
I have a class myData that I want to implement Serializable interface. class myData has only two fields: Integer iData1, String sData2.
Could anybody shown me how my myData class should be?
Thanks a lot!Hey, if you have yet to obtain a remote reference from the app server ...then we are into pandora's box. I lost three whole heads of hair getting up on JBoss when I first started. You want to check out the JBoss forums on the JBoss website, and the enterprise javabeans forum here. Search some posts and read the free JBoss manual.
Unfortunately, there isn't a 'here, do this' solution to getting connected with JBoss. There are quite a few gotcha's. There are descriptors, descriptor syntax ...and this changes between releases so there seems to be alot of people saying 'here, do this' ...but you try and it doesn't work (wrong release). Here are some descriptors that I threw up recently for someone ...a place to start.
http://forum.java.sun.com/thread.jsp?forum=13&thread=414432
This drove me nuts until it all worked right. I was stuck for three weeks at one point ...ready to give up, but then I got it. Perservere ...its a nice container for learning in (its free!).
I will try and watch for you.
Oh, and put something in your head ...at least then you will keep your hair !
:) -
Compile-time warning during javac of a Class that implements Comparable
Hello All,
I have defined a class as follows;
public class CardTiles extends JButton implements Comparable{
During normal compilation with javac, it tell me to use Xlint to compile and the warning it throws is below:
CardTiles.java:4: warning: [serial] serializable class CardTiles has no definition of serialVersionUID
public class CardTiles extends JButton implements Comparable{
^
1 warning
What does this warning mean?
Many thanks!ejp wrote:
you can choose to to differentiate between various versions of your CardTiles classThat's back to front. Serialization will always do that unless you stop it, which you can do via a fixed serialVersionUID. This tells Serialization that different versions of your class are compatible under serialization.I suppose I see it this way because I wouldn't have a serializable object without an ID. Without having an explicit ID the process isn't as transparent to me. It's the same sort of thing as using braces for statements when they're not necessary, e.g.
if(check)
System.out.println("check is on");
else
System.out.println("check is off"); versus
if(check) {
System.out.println("check is on");
} else {
System.out.println("check is off");
}
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