crazyStart :
I am trying to learn Multi threading and for practice, I am trying to print odd & even number using two thread. I have created an object which will act as a lock for the both the threads. When I try to execute it throws java.lang.IllegalMonitorStateException
.
class EVENODDimpl implements Runnable {
int num;
int temp = 0;
Object lock = new Object();
public EVENODDimpl( int num) {
this.num = num;
}
public void run() {
try {
synchronized (lock) {
while(temp<num) {
temp++;
System.out.println(Thread.currentThread().getName()+" "+temp);
this.notify();
this.wait();
}
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
Main Method:
public class EVENODD {
public static void main(String[] args) {
int i = 10;
EVENODDimpl ei = new EVENODDimpl(i);
Thread t1 = new Thread( ei,"EvenThread");
Thread t2 = new Thread( ei,"OddThread");
t1.start();
t2.start();
try {
t1.join();
t2.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
Krzysztof Cichocki :
You wait
and notify
on this
, but you should wait
and notify
on lock
because you synchronize on lock
, you can't wait
and notify
on other object than the one on which you're synchronizing, working version:
class EVENODDimpl implements Runnable {
int num;
int temp = 0;
Object lock = new Object();
public EVENODDimpl( int num) {
this.num = num;
}
public void run() {
try {
synchronized (lock) {
while(temp<num) {
temp++;
System.out.println(Thread.currentThread().getName()+" "+temp);
lock.notify();
lock.wait();
}
}
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
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