此方法返回活动线程的当前线程的线程组中的数量。
public class AtomicIn {
static AtomicInteger count = new AtomicInteger(0);
public static void increment() {
count.getAndIncrement();// 先返回在++
System.err.println(Thread.currentThread().getName() + "--" + count + "-----");
}
public static void main(String[] args) {
for (int i = 0; i < 5; i++) {
Thread t = new Thread(new Th1());
t.start();
}
System.err.println("**********" + Thread.activeCount());
while (Thread.activeCount() > 1) {
Thread.yield();
}
System.err.println(AtomicIn.count);
}
}
class Th1 implements Runnable {
@Override
public void run() {
AtomicIn.increment();
try {
Thread.sleep(500);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
}
代码运行结果
Thread-0--3-----
Thread-1--3-----
Thread-2--3-----
**********6
Thread-3--4-----
Thread-4--5-----
5