Need to count n seconds and change value

[justride]

Hi all,

I have an instanc of this class A that does some things... Other instances of other classes access this instance A all the time, specificly a hashtable of data. I need to reset this hashtable every 8 seconds. Without setting a delay, how can I do this. Do I need to create another instance of soem time counter or something, count 8 seconds then return to instance A?

Could somebody offer advice?

Thanks
Chris

 

[justride]

Oh yea, Instance A needs to be accessible at all times.

Thanks

 

[justride]

And I need to be able to halt the 8 second count and start over at anytime.

 

[wangdong]

Have u tried javax.swing.Timer?

  int delay = 8000; //milliseconds
  ActionListener taskPerformer = new ActionListener() {
      public void actionPerformed(ActionEvent evt) {
          //...Perform a task...
      }
  };
  new Timer(delay, taskPerformer).start();

Chinese Java Faq Forum

http://www.4ugo.com/bbs/index.asp

 

[justride]

I am implementing Timer and TimerTask. Thanks for the advice, I will post if I have any issues.

 

[stefanwagner]

I guess you should synchronize the Hashtable, while clearing:

synchronized (hashtable)
{
        hashtable.clear ();
}

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[timw]

Stefan, Hashtable is already internally synchronized.

Tim

 

[justride]

Here is the deal,

Everytime my propertychanged method is called, I want to restart the 8 second timer so I do this:

 _transTimer = new Timer();
 _transTimer.schedule(new TransactionTimerTask(this),8000);

Before I was cancelling the existign task before creating a new one but I was receving an exception that I cannot start a cancelled task.

Anyways, this way works, and my hashtable clears every 8 seconds, but sometimes the timing is off, off my a bit, so I am thinking that this may not be the perfect way to do this.

For example, if I call this property change method 4 seconds into a scheduled task, then my new task doesnt appear to run for a new 8 seconds, it seems to only run for the remaining 4 of the last task.

Does anybody know how I can stop the existing task and start a new one for 8 seconds?

This could be the right way and I am just experiencing delays because there are a lot of other things going on but I am not quite sure.

Thanks

 

[justride]

Oh yea, the "this" instance contains the resetHashtable() method.

 

[justride]

Hello,

I just did some serious testing. It seems that new tasks do not get scheduled properly. I need to somehow, disregard the previous task if a new one comes in within 8 seconds of the last task. My logic is only working if new tasks come in after 8 seconds.

Thanks

 

[stefanwagner]

Well - I remember the usage of Vector and Hashtable was discouraged because they are internally synchronized, but without reaching the goal.

But I don't find any hint in the documentation - perhaps they fixed these bugs.

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[justride]

I appear to have this working now, after cancelling the task I set it to null before proceeding to the recreation.