Java原子类中的AtomicInteger类详解

public class MyThread extends Thread {
     //static int a = 0;
    static AtomicInteger a = new AtomicInteger();// 表示整数0

    @Override
    public void run() {
        for (int i = 0; i < 200000; i++) {
            // a++;
            a.getAndIncrement();
        }
        System.out.println("子线程执行完毕");
    }
}

public class Test {
    public static void main(String[] args) throws InterruptedException {

        // 案例:一条子线程和一条主线程都对共享变量a进行++操作,每条线程对a++操作400000次
        new MyThread().start();

        for (int i = 0; i < 200000; i++) {
            //MyThread.a++;
            MyThread.a.getAndIncrement();
        }

        // 为了保证子线程和主线程都执行完毕
        Thread.sleep(3000);

        // 打印最终共享变量a的值(子线程,主线程对a的操作都执行完毕了)
        System.out.println("最终:"+ MyThread.a.get());

  }
}

public class MyThread extends Thread {
    public static int[] arr = new int[1000];

    @Override
    public void run() {
        for (int i = 0; i < arr.length(); i++) {
            arr[i]++;
        }
        System.out.println("结束");
    }
}

public class Demo {
    public static void main(String[] args) throws InterruptedException {
        for (int i = 0; i < 1000; i++) {
            new MyThread().start();//创建1000个线程，每个线程为数组的每个元素+1
        }

        Thread.sleep(1000 * 5);//让所有线程执行完毕

        System.out.println("主线程休息5秒醒来");
        for (int i = 0; i < MyThread.arr.length; i++) {
            System.out.println(MyThread.arr[i]);
        }
    }
}

public class MyThread extends Thread {
 
    //改用原子类，使用数组构造
    public static AtomicIntegerArray arr = new AtomicIntegerArray(1000);
    @Override
    public void run() {
        for (int i = 0; i < arr.length(); i++) {
            arr.addAndGet(i, 1);//将i位置上的元素 + 1
        }
        System.out.println("结束");
    }
}

  public class Demo {
      public static void main(String[] args) throws InterruptedException {
          for (int i = 0; i < 1000; i++) {
              new MyThread().start();
          }
          Thread.sleep(1000 * 5);//让所有线程执行完毕
  
          System.out.println("主线程休息5秒醒来");
          for (int i = 0; i < MyThread.arr.length(); i++) {
              System.out.println(MyThread.arr.get(i));
          }
      }
  }