Thread help please!

[sun par]

public class TestClass implements Runnable
{
  int x = 0, y = 0;
  public void run()
  {
    while(true)
    {
      x++; y++;
      System.out.println(" x = "+x+" , y = "+y);
    }
  }
  public static void main(String[] args)
  {
    TestClass tc = new TestClass();
    new Thread(tc).start();
    new Thread(tc).start();
  }
}

Consider the above program. I am totally confused. Are not two threads created. so will each thread not have its own copy of x and y?
Thanks.

[Corey McGlone]

You do, indeed, create two threads, but you're only creating one instance of the class TestClass, which contains your x and y variables. As you're passing a reference to the same TestClass object to each thread, each thread has a reference to a single, shared object and, likewise, shared x and y variables.
Had you done this:

TestClass tc1 = new TestClass();
TestClass tc2 = new TestClass();
new Thread(tc1).start();
new Thread(tc2).start();

Then each thread would have a reference to a unique TestClass object and they would, in turn, have their own x and y variables.
I hope that helps,
Corey

[sun par]

Thanks Corey