The code snippet in 《Java Concurrency in Practice》 :
public class NoVisibility {
private static boolean ready;
private static int number;
private static class ReaderThread extends Thread{
public void run(){
while(!ready)
Thread.yield();
System.out.println(number);
}
}
public static void main(String[] args) {
new ReaderThread().start();
number = 42;
ready = true;
}
}
In this book, the author said "NoVisibility class may print 0 or 42", but I ran this code several times, the result is always 42.