public static void main (String[] args) {
final Object obj = new Object();
Runnable r = new Runnable () {
public void run () {
while (true) {
try {
System.out.println ("-- this lines are being printed in another thread.." + Thread.currentThread ().getName ());
synchronized(obj){// The current thread must own this object's monitor see javadoc guys..Object.wait ();
obj.wait();// just wait for somebody else to awake you here.
}
} catch (Exception ex) {
System.out.println (" -- Interrupted...");
ex.printStackTrace ();
}
}
}
};
new Thread (r).start ();//we crated and started a lazy guy here
new Thread (r).start ();//another lazy guy
new Thread (r).start ();//this can be me :)
while (true) {
System.out.println (" -- this lines are bing printed in main thread.." + Thread.currentThread ().getName ());
try {
Thread.currentThread ().sleep (5000);//Our master will sleep for 5 seconds
synchronized(obj){//same reason with above synchronized
obj.notifyAll();// Then it will say others wake up !
}
Thread.currentThread ().sleep (500);//If we don'T stop the main thread here it will be the owner of the monitor of obj object always.
//It is in a while loop.Others will be blocked on synchronized statement.
} catch (InterruptedException ex) {
ex.printStackTrace();
}
}
}
}
---| Lets look at to the system out , I have took a thread dump for u also |-----
-- this lines are being printed in another thread..Thread-0-- this lines are being printed in another thread..Thread-1
-- this lines are bing printed in main thread..main
-- this lines are being printed in another thread..Thread-2
-- this lines are being printed in another thread..Thread-0
-- this lines are being printed in another thread..Thread-1
-- this lines are bing printed in main thread..main
-- this lines are being printed in another thread..Thread-2
-- this lines are being printed in another thread..Thread-0
-- this lines are being printed in another thread..Thread-1
Full thread dump Java HotSpot(TM) Server VM (1.5.0_08-b03 mixed mode):
"Thread-2" prio=1 tid=0x09dcaa88 nid=0xfa6 in Object.wait() [0x6e8cb000..0x6e8cc080]
at java.lang.Object.wait(Native Method)
- waiting on <0xaa00e258> (a java.lang.Object)
at java.lang.Object.wait(Object.java:474)
at sil.WaitNotifyExample$1.run(WaitNotifyExample.java:17)//obj.wait()
- locked <0xaa00e258> (a java.lang.Object)
at java.lang.Thread.run(Thread.java:595)
"Thread-1" prio=1 tid=0x09dc9218 nid=0xfa5 in Object.wait() [0x6e94c000..0x6e94d100]
at java.lang.Object.wait(Native Method)
- waiting on <0xaa00e258> (a java.lang.Object)
at java.lang.Object.wait(Object.java:474)
at sil.WaitNotifyExample$1.run(WaitNotifyExample.java:17)//obj.wait()
- locked <0xaa00e258> (a java.lang.Object)
at java.lang.Thread.run(Thread.java:595)
"Thread-0" prio=1 tid=0x09dcb550 nid=0xfa4 in Object.wait() [0x6e9cd000..0x6e9cdd80]
at java.lang.Object.wait(Native Method)
- waiting on <0xaa00e258> (a java.lang.Object)
at java.lang.Object.wait(Object.java:474)
at sil.WaitNotifyExample$1.run(WaitNotifyExample.java:17)//obj.wait()
- locked <0xaa00e258> (a java.lang.Object)
at java.lang.Thread.run(Thread.java:595)
"main" prio=1 tid=0x09cecee0 nid=0xf94 waiting on condition [0xbfe77000..0xbfe776f8]
at java.lang.Thread.sleep(Native Method)
at sil.WaitNotifyExample.main(WaitNotifyExample.java:37)//Thread.currentThread ().sleep (500)
