URGENT: How to run threads in sequence?

Question

Dear experts, I am new to writing threads. I would like to know how to run threads in sequence? How do I know when a thread finishes its task?
In the following code, classes Process_A(), Process_B(), Process_C() and Process_D() are subclasses of Class Thread.
I'd like to know if I am using the join() function correctly? My intention is to wait for the previous process to finish before running the current process.
Could anyone kindly give me some solutions on how to run the processes in sequence?
Thanks!!
=============================================================
Thread process;
Vector process_names = new Vector();
process_names.add("a");
process_names.add("b");
process_names.add("c");
for(int i=0; i<process_names.size(); i++)
String process_name = (String) process_names.elementAt(i);
if(process_name.equals("a"))
process = new Process_A();
else if(process_name.equals("b"))
process = new Process_B();
else if(process_name.equals("c"))
process = new Process_C();
else if(process_name.equals("d"))
process = new Process_D();
timer = new javax.swing.Timer(1000, new ProcessListener());
timer.start();
// ProcessListener()
class ProcessListener implements ActionListener {
public void actionPerformed(ActionEvent evt) {
if(process!=null)
if(process.isAlive())
try
process.join();
catch(Exception ex)
ex.printStackTrace();
process.start();

Answer 1

just look at this simple example u will get to know how to use join method
This does exactly what u want
class callme
void call(String msg)
System.out.println("["+msg);
Try
Thread.sleep(1000);
catch(InterruptedException e)
System.out.println("interrupted");
System.out.println("]");
class caller implements Runnable
String msg;
Callme target;
Thread t;
Public Caller(Callme targ, String s)
target=targ;
msg=s;
t=new Thread(this);
t.start();
public void run()
target.call9msg);
class Synch
public static void main(String arg[])
Callme target=new Callme();
Caller ob1=new Caller(target,"hello");
Caller ob2=new Caller(target,"Synchronized");
Caller ob3=new Caller(target,"world");
Try
ob1.t.join();
ob2.t.join();
ob3.t.join();
catch(InterruptedException e)
System.out.println("interrupted");
waiting for dukes