java多线程累加计数的实现方法

public class Test {
 //公共变量
 int count=0;
 public static void main(String[] args){
  //new一个实现Runnable的类
  Test test=new Test();
  //创建5个任务
  MyRunnable myRunnable1=test.new MyRunnable();
  MyRunnable myRunnable2=test.new MyRunnable();
  MyRunnable myRunnable3=test.new MyRunnable();
  MyRunnable myRunnable4=test.new MyRunnable();
  MyRunnable myRunnable5=test.new MyRunnable();
  //创建5个线程
  new Thread(myRunnable1).start();
  new Thread(myRunnable2).start();
  new Thread(myRunnable3).start();
  new Thread(myRunnable4).start();
  new Thread(myRunnable5).start();
 }
 //创建一个实现Runnable的类
 class MyRunnable implements Runnable{
  public void run() {
   while(true){
    //锁住的是整个MyRunnable类
    synchronized(MyRunnable.class){
     if(count>=1000){
      break;
     }
     System.out.println(Thread.currentThread().getName()+":count:"+(++count));
     //测试时，线程更容易切换
     Thread.yield();
    }    
   }
  }  
 } 
}

public class Test {
 //公共变量
 int count=0;
 public static void main(String[] args){
  //new一个实现Runnable的类
  Test test=new Test();
  //创建1个任务
  MyRunnable myRunnable1=test.new MyRunnable();
//  MyRunnable myRunnable2=test.new MyRunnable();
//  MyRunnable myRunnable3=test.new MyRunnable();
//  MyRunnable myRunnable4=test.new MyRunnable();
//  MyRunnable myRunnable5=test.new MyRunnable();
  //创建5个线程
  for(int i=0;i<4;i++){
   new Thread(myRunnable1).start();
  }
//  new Thread(myRunnable2).start();
//  new Thread(myRunnable3).start();
//  new Thread(myRunnable4).start();
//  new Thread(myRunnable5).start();
 }
 //创建一个实现Runnable的类
 class MyRunnable implements Runnable{
  public void run() {
   while(true){
    //锁住的是同一对象
    synchronized(this){
     if(count>=1000){
      break;
     }
     System.out.println(Thread.currentThread().getName()+":count:"+(++count));
     //测试时，线程更容易切换
     Thread.yield();
    }
    
   }
  }  
 }
}

public class Test {
    static CountDownLatch cdl=new CountDownLatch(1000);;
    static AtomicInteger ai=new AtomicInteger(0);
    public static void main(String[] args) throws InterruptedException{ 
     ExecutorService exec=Executors.newFixedThreadPool(100);
       for (int i = 0; i < 1000; i++) {
        exec.execute(new Runnable() {
    @Override
    public void run() {
     System.out.println(Thread.currentThread().getName()+":"+ai.getAndIncrement());
     cdl.countDown();
    }
   });
          }
     cdl.await();
     System.out.println(ai.get());
     exec.shutdown();
    } 
}