在多线程下，如果对一个数进行叠加，该怎么做？

在多线程下，如果对一个数进行叠加，该怎么做？

/*两种方法一种是加锁（锁可以使用Sychorized和ReentrantLock），一种是使用Atomic下的线程安全的类。*/
   public class Volatile {
       private static CountDownLatch countDownLatch = new CountDownLatch(10);
       public int inc = 0;
       Lock lock = new ReentrantLock();


       public void increase() {
           lock.lock();
           try {
               inc++;
           } finally {
               lock.unlock();
           }
       }

       public static void main(String[] args) {
           final Volatile aVolatile = new Volatile();
           for (int i = 0; i < 10; i++) {
               new Thread() {
                   public void run() {
                       for (int j = 0; j < 1000; j++) {
                           aVolatile.increase();
                       }
                       countDownLatch.countDown();
                   }

               }.start();
           }

           try {
               countDownLatch.await();
           } catch (InterruptedException e) {
               e.printStackTrace();
           }
           System.out.println(aVolatile.inc);
       }
   }

   Volatile {
       private static CountDownLatch countDownLatch = new CountDownLatch(10);
       public AtomicInteger inc = new AtomicInteger();  //

       public void increase() {
           inc.getAndIncrement();//对inc  进行原子性++的一个方法  i++
       }
       public static void main(String[] args) {
           final Volatile test = new Volatile();
           for (int i = 0; i < 10; i++) {
               new thread() {
                   public void run() {
                       for (int j = 0; j < 1000; j++) {
                           test.increase();
                       }
                       countDownLatch.countDown();
                   }
               }.start();
           }

           try {
               countDownLatch.await();
           } catch (InterruptedException e) {
               e.printStackTrace();
           }
           System.out.println(test.inc);
       }
   }