public class SyncTest implements Runnable {
static int counter;
public void run() {
Object lock = SyncTest.class;
for (int n = 0; n < 1000000; n++)
synchronized (lock) {
counter++;
}
}
public static void main(String[] args) {
SyncTest test = new SyncTest();
Thread[] thr = new Thread[4];
for (int n = 0; n < thr.length; n++) {
thr[n] = new Thread(test);
thr[n].start();
}
for (int n = 0; n < thr.length; n++) {
try {
thr[n].join();
} catch (InterruptedException ex) {
}
}
System.out.println(counter == 1000000 * thr.length ?
"ok" : "fail: " + counter);
}
}