JAVA同期コードブロックsynchronized

/*

JAVA                    

       

synchronized(  )//           
{
	        
}

     ，              
           CPU    ，    


     ：
1，               
2，             
	
                 

  ：           

  ：         ，      
*/

class Tick implements Runnable
{
	private int tick = 50;

	Object obj = new Object();//      

	public void run()
	{

		while(true)
		{
			synchronized(obj)
			{
				if(tick > 0)
				{
					//try{Thread.sleep(40);}catch(Exception e){}
					System.out.println( Thread.currentThread().getName() + " sail --" + tick--);
				}	
			}
		}
	}
}

class TickDemo
{
	public static void main(String []args)
	{
		Tick t = new Tick();

		Thread t1 = new Thread(t);
		Thread t2 = new Thread(t);
		Thread t3 = new Thread(t);
		Thread t4 = new Thread(t);

		t1.start();
		t2.start();
		t3.start();
		t4.start();

	}
}