Re: Java Thread Problem

Lew <>
Fri, 21 Mar 2008 07:43:06 -0400
Sanny wrote:

I use a thread to call a function in a new thread.

Here is the code I use

But only fragments of it. You need to provide an SSCCE.

 private Thread runner2;

public void start2(){
  runner2 = new Thread(this);

Do not muck with Thread priorities here.


and in run of thread

 public void run(){

Thread thisThread = Thread.currentThread();

If you only use 'thisThread' once, for the comparison, you have no need for
the variable. Just use the currentThread() expression directly.

if (runner2==thisThread){

This check-and-set idiom will fail, absent some form of synchronization.


Do not set Thread priorities until you know more about how threads work.


Since you're already seen to be calling a function, this isn't a great name
for a method. Also, use camel case in the name.






start2();to start a new thread

Is this supposed to be part of the code snippet, or part of the narrative?



Do you read the API docs? You should.

**Deprecated.** ... the method was never implemented.
If if were to be implemented, it would be deadlock-prone


   }catch (NullPointerException e){
    //System.out.println("Bad URL: "+page);

As shown, the code is guaranteed to throw this exception. Well, nearly
guaranteed; concurrency anomalies might actually prevent the exception.


I use start2() to start a new runner2 thread.

But my Question is When I call the function to start a new thread Will
the Original thread runner2 stopped or a new thread runner2 will be

I want that runner2 thread first stop and then start a new thread
runner2. How to destroy a thread and start it again.

Why would you want to destroy the thread? Why start it at all if you're
planning to destroy it? I don't understand.

Once I call runner2.destroy, will that thread stops? And in case I

What thread? You have runner2 set to null, unless a concurrent action somehow
breaks through the memory barrier and changes it.

Even if runner2 referenced a Thread, the destroy() wouldn't stop it, because
"the method was never implemented"!

start a new thread runner2 will the old thread destroy both old & new
threads as both use same variable runner2?

There is a difference between the variable and the object to which it points.
  Actions come from objects, not variables.


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