display data for a thread of many threads

[Qusay Jaafar]

Hi,
I have a text field for entering a number. I have a start button and stop button. I have another button which is "Display".
User types number (e.g 101) into the text field then clicks start button, a thread starts with name thread.setName("101"); Now, the user types number (e.g 102) another thread will start when click on start button with name thread.setName("102");
Those two threads reading data changed continously (may be counter).
Clicking Display button will show the data for the selected thread (which was typed into the text field) and display it onto a display panel.
Stop button will stop the selected thread (which was typed into the text field)
I have the idea about creating a thread and wrapping it in order to work within the event dispatch thread BUT I cannot make all these ideas together.
Please, any help?

[Ernest Friedman-Hill]

Sounds like a homework assignment.

Show us what you have so far. Where are you stuck?

[Qusay Jaafar]

Not really, I am working within a project for a network company. I am reading sent and received bytes from a specific port of a switch. So, I am thinking here to create a thread for each port for reading the data continuously and that is the purpose of start button. stop button will stop that thread which is typed in the text field. display button will read the thread which is typed in the text field and read the value of the bytes of that port.
I created a ThreadFactory pattern for each button which I think I don't need it for one of them.
click on start button will create a thread and I put it into a hashMap.
click on display button will search the hashMap for that thread and suppose to read the bytes for that port.
I think creating threads for each port of the switch that because of the counter for a port will reset (starts again from zero) when the bytes reached for that port 4GB. So, creating a thread for a port will keep reading the bytes.
is my approach reasonable?
and BTY, I read the last tech tip of MultiThreading in Swing
it used another approach for handling event dispatch thread and that by using Timer class.

[Qusay Jaafar]

Hi,
I just read a reply for a message. The last reply for this message was from Ernest which was:
(The purpose of the ThreadLocal class is indeed to create variables that are specific to a thread, but it's used for member or static variables. As has already been (correctly) stated in this thread, the local variables of a method, static or not, are unique to that single method invocation, and are never shared with any other invocation on the same or any other thread.)

do you think using ThreadLocal will solve my problem?

[Ernest Friedman-Hill]

I don't know what problem you're having. The thing with the HashMap sounds fine -- why doesn't that work?

[Qusay Jaafar]

the code below can show you the main idea of what I am doing.
if new ActiveThread("1") starts then bytes in SwitchData will be changed. Now, if new ActiveThread("2") starts then bytes in SwitchData will be changed againd. Now, if new ActiveThread("1") called from the hashMap then bytes is something different than what it should be.

I am thinking now to use ThreadLocal instead of Thread class.

your suggestions please...

class SwitchData {
 
String switchIP;
String bytes;
 
public SwitchData(String host) {
 
this.switchIP = host;
}
 
public void retrieveData(String oid) {
 
// code using snmp package for retrieving data
// 
// bytes = what is retrieved from receive or send oid
}
 
public String getBytes() {
 
return bytes;
}
} // end class SwitchData
 
public class SwitchMonitor {
 
ActiveThread active;
 
public SwitchMonitor() {
 
// text field for typing port number
// activate button that reads port number from the text field
 
activate.addActionListener( new ActionListener() {
public void actionPerformed(ActionEvent e) {
 
active = new ActiveThread(txtField.getText());
                                active.start();
}
 
public static void main(String[] args) {
 
new SwitchMonitor();
}
} // end class SwitchMonitor
 
class ActiveThread extends Thread {
 
public ActiveThread(String port) {
 
this.port = port;
}
 
public void run() {
 
// code for storing in a HashMap
// may be not necessary !
 
SwitchData data = new SwitchData(switchIPaddress);
 
data.retrieveData(sendOrReceiveOIDforPort);
 
String bytes = data.getBytes();
 
System.out.println("bytes: " + bytes);
}
} // end class ActiveThread
  

[Ernest Friedman-Hill]

Originally posted by Qusay Jaafar:
the code below can show you the main idea of what I am doing.
if new ActiveThread("1") starts then bytes in SwitchData will be changed. Now, if new ActiveThread("2") starts then bytes in SwitchData will be changed againd. Now, if new ActiveThread("1") called from the hashMap then bytes is something different than what it should be.

I don't see how this could be. Each ActiveThread has its own instance of the SwitchData class, and each SwitchData instance has its own bytes member, so there will be no interference between them -- unless in your real code, you've got some static variables.