Hi Saidamin
It seems to me that the 1st thread starts and calls
DateAndTime.show(...). This action locks the access of other threads to
this method until the end of its execution by the first thread.
When the 2nd thread starts, the method is locked and the thread must
wait. According to the implementation of the "retry" mechanism (we may
guess that the thread sleeps some time and tries again), it may miss
the moment when the method is released and it will be the third thread
that passes first (as it was started at the right moment).
The moral of this behavior is that when more than one thread are waiting
in queue for running a locked synchronized method, the execution order
may be unpredictable.
Hope it helps
Mihai
Saidamin Usmanov a écrit :
Hello Everyone,
I am doing home work on Thread part.
I have following classes:
public class MyCurrentDate implements Runnable{
Thread thread;
String name;
public MyCurrentDate(String thr){ name = thr;
thread = new Thread(this);
thread.start();
}
public void run() { DateAndTime.show(name);
}
}
import java.util.Date;
public class DateAndTime {
static synchronized void show(String thr) {
for(int i = 0; i < 5; i++){
System.out.println(thr + ": " + String.format("%tc", new
Date()));
}
try {
Thread.sleep(100);
} catch (InterruptedException e) {} }
}
When I run following code
public class Main {
public static void main(String[] args) {
new MyCurrentDate("Thread 1");
new MyCurrentDate("Thread 2");
new MyCurrentDate("Thread 3");
}
}
I get
Thread 1: Sun Jun 20 16:28:05 EDT 2010
Thread 1: Sun Jun 20 16:28:05 EDT 2010
Thread 1: Sun Jun 20 16:28:05 EDT 2010
Thread 1: Sun Jun 20 16:28:05 EDT 2010
Thread 1: Sun Jun 20 16:28:05 EDT 2010
Thread 3: Sun Jun 20 16:28:05 EDT 2010
Thread 3: Sun Jun 20 16:28:05 EDT 2010
Thread 3: Sun Jun 20 16:28:05 EDT 2010
Thread 3: Sun Jun 20 16:28:05 EDT 2010
Thread 3: Sun Jun 20 16:28:05 EDT 2010
Thread 2: Sun Jun 20 16:28:05 EDT 2010
Thread 2: Sun Jun 20 16:28:05 EDT 2010
Thread 2: Sun Jun 20 16:28:05 EDT 2010
Thread 2: Sun Jun 20 16:28:05 EDT 2010
Thread 2: Sun Jun 20 16:28:05 EDT 2010
Instead of
Thread 1: Sun Jun 20 16:28:05 EDT 2010
Thread 1: Sun Jun 20 16:28:05 EDT 2010
Thread 1: Sun Jun 20 16:28:05 EDT 2010
Thread 1: Sun Jun 20 16:28:05 EDT 2010
Thread 1: Sun Jun 20 16:28:05 EDT 2010
Thread 2: Sun Jun 20 16:28:05 EDT 2010
Thread 2: Sun Jun 20 16:28:05 EDT 2010
Thread 2: Sun Jun 20 16:28:05 EDT 2010
Thread 2: Sun Jun 20 16:28:05 EDT 2010
Thread 2: Sun Jun 20 16:28:05 EDT 2010
Thread 3: Sun Jun 20 16:28:05 EDT 2010
Thread 3: Sun Jun 20 16:28:05 EDT 2010
Thread 3: Sun Jun 20 16:28:05 EDT 2010
Thread 3: Sun Jun 20 16:28:05 EDT 2010
Thread 3: Sun Jun 20 16:28:05 EDT 2010
Does anyone know how to fix the problem?
Thank you in advance,
Saidamin Usmanov
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