Read field stale value after object construction

Question

I\'m reading a book "Java concurrency in practice" by Brian Goetz. Paragraphs 3.5 and 3.5.1 contains statements that I can not understand.

Consider the followin

Answer 1

You are probably trying to simulate a concurrency scenario, which I believe is very hard to simulate using a couple of threads.

The following test-case which you have written is not correct at all is more likely to throw a NullPointerException.

public class Tests {

  private HolderContainer hc = new HolderContainer();

  class Initialization implements Runnable {
    public void run() {
      hc.init();
    }
  }

  class Checking implements Runnable {
    public void run() {
      hc.holder.assertValue();
    }
  }

  public void run() {
    new Thread(new Initialization()).start();  
    new Thread(new Checking()).start(); 
  }
}

What if your Checking Thread executes before Initialization one?? Also putting a sleep there simply means that executing thread will sleep and does tell you about the internal atomic operations being performed by then.