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How can I achieve this?

I have a class "task", which has a method called "evaluate()". When this method is called and there is a state change, this Task will notify other Tasks. (The other tasks would in turn evaluate and notify some other tasks if evaluation return true).

my preliminary idea is to use thread's notification methods. But is there any other easier or more neat way to accomplish this?

thanks.
0
ggyao2003
Asked:
ggyao2003
1 Solution
 
mmuruganandamCommented:
You have Observer and Observable

Have a look at this... for more information..

http://www.javaworld.com/javaworld/jw-10-1996/jw-10-howto.html
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WebstormCommented:
Hi ggyao2003,

You can define a listener interface, for example:

    public interface TaskListener
    {
         public void notifiedByTask(Task source  /* , ... other needed parameters */ );
    }

And implements this interface in your task class:

    public class Task
    implements TaskListener
    {
          public void notifiedByTask(Task source  /* , ... other needed parameters */ )
          {
              ...
          }

          private Vector listeners=new Vectors(); // keep listener references

          public void addTaskListener(TaskListener tl)
          {
                if (!listeners.contains(tl)) listeners.add(tl);
          }

          public void removeTaskListener(TaskListener tl)
          {
                listeners.remove(tl);
          }

          private void notifyListeners()
          {
                int nb=listeners.size();
                for (int i=0;i<nb;i++)
                      ( (TaskListener)listeners.elementAt(i) ).notifiedByTask(this, ... );
          }
    }


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rama_krishna580Commented:
try here you will get lot of stuff...

http://venus.cs.depaul.edu/Java/chap08.html

R.K
0
 
ggyao2003Author Commented:
webstorm's advice is the easiest to implement in my case. It is really really simple.
thanks.
0
 
ggyao2003Author Commented:
oops...
I made a mistake in my previous post. It should be "mmuruganandam" instead of "webstorm".
But webstorm did gave a great suggestion!
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