Updating a GUI component from a runnable class that doesn't know that GUI
Hi. I have a problem that I think isn't solvable in an elegant way, but I'd like to get confirmation before I do it the dirty way.
My application allows the user to save (and load) his work in sessions files. I implemented this by a serializable class "Session" that basically stores all the information that the user created or the settings he made in its member variables.
Now, I obviously want the session files created by this to be as small as possible and therefore I made sure that no GUI components are stored in this class.
When the user has made all his settings, he can basically "run" his project, which may last for a long time (minutes, hours or days, depending on what the user wants to do....). Therefore I need to update the GUI with information on the progress/outcome of the running project. This is not just a matter of updating one single GUI component, but of a dynamic number of different internal frames and panels. So I'd need a reference to a GUI component that knows all these subcomponents to run a method that does the update work.
How do I do that? I cannot pass the reference to that component through the method's argument that "runs" the project, because that needs to be a seperate thread, meaning that the method is just the run() method of that thread which has no arguments (which I cannot modify if I'm not mistaken).
So the only thing I can think of is passing the reference through the constructor of the runnable class (which in turn must be stored in the session because it contains critical information on the user's work). As a result, all components that need to be incorporated in that updating process would be part of the session and go into the exported file, which is exactly what I wanted to avoid.
I hope this description makes sense...
Thanks in advance!
Thanks for the quick answer! Though to be honest I am not sure how it relates to my question. Which is probably my fault rather than yours :-)
But sometimes all it takes me to solve my problem is posting it to a forum and reading it through again :)
Now I wrote a seperate class "Runner" that extends thread and has the gui components as members (passed through its constructor). I create and start() that object in the run method of the original runnable class (which isn't runnable anymore) so I can pass the gui component reference through that run method's argument.
Not sure if this is elegant, but at least it allows me to avoid saving gui components to the session file :-)
I am realizing that probably this post shouldn't have gone into the swing forum...
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Hi there,
I'm currently trying to change a GUI component in my 'Application' class from my 'Dice' class.
So the Application class sets up some GUI including a JLabel that initially displays "Change".
The 'Dice' class contains the ActionPerformed() method for when the 'Change' button (made from Application class) is clicked.
And it returns an 'int' between 1 and 6.
Now I want to set this number back int he JLabel from the Application class.
APPLICATION CLASS
import javax.swing.*;
import java.awt.*;
import java.util.Random;
import java.awt.event.*;
public class Application extends JFrame implements ActionListener{
public JPanel rollDicePanel = new JPanel();
public JLabel dice = new JLabel("Loser");
public Container contentPane = getContentPane();
public JButton button = new JButton("Change");
public Dice diceClass = new Dice();
public Application() {}
public static void main(String[] args)
Application application = new Application();
application.addGUIComponents();
public void addGUIComponents()
contentPane.setLayout(new BorderLayout());
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this.setSize(460, 655);
this.setVisible(true);
this.setResizable(false);
public void changeDice()
dice.setText("Hello");
public void actionPerformed(ActionEvent e) {}
}DICE
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Dice implements ActionListener
public Dice() {}
public void actionPerformed(ActionEvent e)
//super.actionPerformed(e);
String event = e.getActionCommand();
if(event.equals("Change"))
System.out.println("Will be about to change the 'dice' label");
Application application = new Application();
application.dice.setText("Hello");
}It's all about references, baby. The Dice object needs a way to communicate with the Application object, and so Dice needs a reference to Application. There are many ways to pass this. In my example I pass the application object directly to Dice, but a better way would use interfaces and some indirection. Look up the Observer pattern for a better way to do this that scales much better than my brute-force approach.
import javax.swing.*;
import java.awt.*;
public class Application extends JFrame // *** implements ActionListener
// *** make all of these fields private ***
private JPanel rollDicePanel = new JPanel();
private JLabel dice = new JLabel("Loser");
private Container contentPane = getContentPane();
private JButton button = new JButton("Change");
// *** pass a reference to your application ("this")
// *** to your Dice object:
private Dice diceClass = new Dice(this);
public Application()
public static void main(String[] args)
Application application = new Application();
application.addGUIComponents();
public void addGUIComponents()
contentPane.setLayout(new BorderLayout());
rollDicePanel.add(dice);
button.addActionListener(diceClass);
contentPane.add(rollDicePanel, BorderLayout.SOUTH);
contentPane.add(button, BorderLayout.NORTH);
setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
setPreferredSize(new Dimension(460, 655));
pack();
setLocationRelativeTo(null);
setVisible(true);
setResizable(false);
// *** I'm not sure what this is supposed to be doing, so I commented it out.
//public void changeDice()
//dice.setText("Hello");
// *** ditto. I strongly dislike making a GUI class implement ActionListeenr
//public void actionPerformed(ActionEvent e)
// *** here's the public method that the Dice object calls
public void setTextDiceLabel(String text)
dice.setText(text);
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
public class Dice implements ActionListener
// *** have a variable that holds a reference to your application object
private Application application;
private boolean hello = true;
public Dice(Application application)
// *** get that reference via a constructor parameter (one way to do this)
this.application = application;
public void actionPerformed(ActionEvent e)
String event = e.getActionCommand();
if (event.equals("Change"))
System.out.println("Will be about to change the 'dice' label");
if (hello)
// *** call the application's public method
application.setTextDiceLabel("Hello");
else
application.setTextDiceLabel("Goodbye");
hello = !hello;
//Application application = new Application();
//application.dice.setText("Hello");
} -
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2009-001 Security Update Has Broken Printing From VMWare
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I've installed Adobe Reader 8 since the update, and that won't print too, though I can still print PDF's from Preview, perhaps the update has affected CUPS.
Since Apple recommend VMWare (quite rightly) in their online store, I hope that they feel an obligation to help solve this!
Message was edited by: Punter1Dave Sawyer wrote:
It seems like you VMWare people have more problems than people using Parallels.
I have both
Me too!
in my experience Parallels is a lot more twitchy and problematic than VMWare.
I'm not sure about the definition of "twitchy" in this (or any) context.
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I am sure that VMWare will find and fix this bug fairly shortly. I'm sure Apple will help them if they ask.
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Im in the middle of developing a program but swing is making it very hard for me to structure my code. The problem is I want to update the text of a Jlable from a different class when a button is pressed. THe event handling is done by a different class than the where the Jlabel is initiated which is why i think it doesnt work. But when the button is pressed it does execute a method from the main class that has the .setText() in it. Why wont the Jlabel update? Thank youThanks for your help but i am still having trouble.
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Morning all.
I'm looking at options we might have open to us for the following scenario. Any ideas? Previous experiences, etc most welcome ...
We have a custom field in DPR_DET_DATA_PROJECT_O that we transfer to PS, but want to use the same field value to force PPM to think the same field change has occurred in DPR_DET_DATA_PHASE_O without us actually needing to access the component via the UI. We have an active subsystem that we write the value to, but don't want to have to a have to start the phase component from the ui to pass the change before saving.
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Many ThanksHello David,
If I understood correctly, you want to change a custom field existing both in the project definition and at phase level, without accessing the Phase in the UI? Is that right?
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Tudor
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