concurrent java code which should expose a visibility bug

Volatile.java

public class Volatile {
  private static boolean ready;
  private static int number;

  public static class ReaderThread extends Thread {
    public void run() {
      while(!ready)
      {
        Thread.yield();
      }
      System.out.println("number is: " + number);
    }
  }

  public static void main(String[] args) {
    new ReaderThread().start();
    number = 42;
    ready = true;
  }
}