How can I pass a boolean to notifyObservers()

[dumb_ass]

Hi everyone, I'm having a problem passing a Boolean object to notifyObservers() method.

class Model extends Observable
{
   .....
   private Boolean booleanValue=new Boolean(false);
   .....
   .....
   public void setBooleanValue()
   {
        this.booleanValue=true
        setChanged();
        notifyObservers(this,this.booleanValue);
   }
}

class View implements Observer
{
     .....
     public void update(Observable o,Object arg)
     {
         //do something
     }
}

From my understandings, whenever the method notifyObservers() is invoked , update() method will be called.
I've no idea why I can't pass the booleanValue to notifyObservers() to make changes in update(). After all, it's just an object, isn't it ? Can someone help me out ?? Thanks everyone in advance.

[pbrockway2]

notifyObservers() is a method implemented by instances of Observable.

In fact there are two such methods: one takes no arguments, the other takes a single Object argument.

Perhaps you mean

  /**
   * Sets the boolean value of the model to a given value and notifies observers.
   */
public void setBooleanValue(boolean b)
{
    booleanValue = b;
    notifyObservers(booleanValue);
}

But that's only a guess. What is the setBooleanValue() method supposed to do?

[azzaiel]

what do you mean by passing a boolean value?
w/ a method from the class View?

you can pass a boolean value if your method return a boolean value

for example

public boolean isScorePass(int score) {
     
     if (score >= 75) {
          return true;
     } else {
         return false;
     }
  
}

[toadaly]

notifyObservers(Object, Object) is not a member of the Observable class, soi I'm guessing it's part of your Model class?

If so, look at that method to try to figure out what's wrong.

[dumb_ass]

Sorry , if I made all of ya guys confused. I'm a total noob and I start working on MVC in java and having a huge huge confusion. The program is, I put a button in the View and its state in the Model. If the button got pressed in View then controller class call setButtonPressed() and change its state in the Model and then Model update all of its observers . The problem is even though I've clicked the button , I've no idea how to get the Boolean value back in the update() method.

import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
import java.util.Observable;
import java.util.Observer;

class Model extends Observable
{
    //the button hasn't been pressed
    private Boolean buttonPressed=new Boolean(false);

    //return the button state whether it's been pressed or not
    public Boolean getButtonPressed()
    {
        return this.buttonPressed;
    }

    //once the button has been pressed the state changes
    public void setButtonPressed(Boolean state)
    {
        this.buttonPressed=state;
        setChanged();
        notifyObservers(this.buttonPressed);
    }
}
class View implements Observer
{

    private JButton aButton=new JButton("Click me");
    private Model model;
    private Controller controller;

    public View(Model model ,Controller controller)
    {
        this.model=model;
        this.controller=controller;
    }
    public void display()
    {
        JFrame window=new JFrame("Window");
        controller=new Controller(this.model);
        this.aButton.addActionListener(controller);
        this.model.addObserver(this);
        this.aButton.setActionCommand("clicked");
        window.add(this.aButton);
        window.pack();
        window.setVisible(true);
    }
    public void update(Observable o, Object arg)
    {
       
      // I'm trying to get the result back from the Model which is "true" boolean value but i dunno how i can do it
    }

}
class Controller implements ActionListener
{
    private Model model;

    public Controller()
    {
        
    }
    public Controller(Model model)
    {
        this.model=model;
    }

    public void actionPerformed(ActionEvent e)
    {
        if("clicked".equals(e.getActionCommand()))
        {
            this.model.setButtonPressed(true);
        }
    }
}
public class Main
{
    public static void main(String args[])
    {
        Model model=new Model();
        Controller controller=new Controller();
        View view=new View(model,controller);
        view.display();

    }
}

[toadaly]

As far as I can tell, it's already working. Maybe you're unfamiliar with the idea of casting? Try this...

   public void update(Observable o, Object arg)
    {

      // I'm trying to get the result back from the Model which is "true" boolean value but i dunno how i can do it

	//like this
	Boolean thisIsYourAnswer = (Boolean) arg;
       	System.out.println("Yep, it's true, see --> "+thisIsYourAnswer);
    }

[paul pasciak]

Your code is a completely working
small scale MVC example.

It does the following:
Visually, the view displays a button
within a frame. When the button is
pressed, it records this status in
the model's variable:

private Boolean buttonPressed;

Your problems is how to display this
status to the outside world. You have
correctly identified the method that
requires code to do this.

public void update(Observable o, Object arg){
// I'm trying to get the result back from the Model
// which is "true" boolean value but i dunno how i
// can do it
}

You do not seem to realize that the
buttonPressed value, and its source
is being automatically delivered to
the "view" by way of:

notifyObservers(Object arg) // in the Model
update(Observable o, Object arg){ // in the View

These methods work hand-in-hand.
HERE IS HOW YOU SHOULD INTERPRETE THE update() METHOD

public void update(model, model.buttonPressed){
// I'm trying to get the result back from the Model
// which is "true" boolean value but i dunno how i
// can do it
}

You can ignore the FACT that this
method is delivering the
buttonPressed object, and its source,
or you can consider it in the code
you design for your answer.
You did not specify a particular motif.
The answer you need can be
provided by a single line of code
within your update() method.