原子类

public class App3 {
    public static void main(String[] args) {
        Task task = new Task();
        Thread t1 = new Thread(task);
        Thread t2 = new Thread(task);
        t1.start();
        t2.start();
    }

}

class Task implements Runnable{
    
    private static AtomicInteger count = new AtomicInteger();
    
    public Integer set(){
        int number = count.incrementAndGet();//每次加1
        System.out.println(number);
        return number;
    } 
    
    public void run() {
        while(true){
            Integer number = set();
            if(count.getAndIncrement() > 200){
                break;
            }
        }
    
    }
}

AtomicInteger  AtomicBoolean  AtomicLong .....都是 java.util.concurrent.atomic 包下面的原子类
原子类是线程安全的，是用了CAS 无锁机制来保证线程的安全